(FORTUNE Magazine) – A pair of signs outside vice chairman Harry Pearce's door on the 39th floor of General Motors' corporate headquarters in Detroit read: STOP. IF YOU HAVE A COLD, FLU, OR UPPER RESPIRATORY INFECTION, PLEASE DO NOT ENTER THIS OFFICE. THANK YOU. Pearce, 56, the former North Dakota litigator who is GM's second-highest executive, is recovering from a malignant blood disorder similar to acute myelogenous leukemia. Because his immune system has been weakened by chemotherapy and a subsequent stem-cell transplant, he wants to limit exposure to potentially life-threatening infections. His disease is now in remission, but it will be at least another 16 months before he can be considered cured; the vast majority of relapses occur within two years of a transplant.

Pearce vaulted to national attention in 1993 by leading GM's attack on NBC, whose Dateline program had rigged a demonstration of a GM pickup truck bursting into flames. Before his illness, he was considered the likely successor to Chairman and CEO Jack Smith, 61, who could announce his retirement as early as the end of this year. Should Pearce still be regarded as Smith's heir apparent? He doesn't see why not. He's already working several days a week and expects to be back in the office full-time by June. "What I owe the corporation is the ability to deliver 100%," Pearce says. "If I can deliver that, leukemia should not be an issue."

Always lean and sinewy, Pearce is several pounds lighter but otherwise shows few signs of his 100-day treatment at the Fred Hutchinson Cancer Research Center in Seattle. His face is slightly puffy, and his skin is irritated by drugs he is taking to reduce side effects from the transplant. In his first major interview since leaving the hospital, Pearce spoke with FORTUNE's Susan Fraker and Alex Taylor III about his illness and how it has changed his life.

"I feel quite good--dramatically better than my first couple of months back, when everything seemed to be difficult physically. I wasn't fully prepared for the impact on my body of the stem-cell transplant. It is nothing that can be very accurately described; you have to experience it. My doctor says you don't really feel like yourself for a year afterward. I'm seven months down that road.

My energy has mostly returned. I can do a couple of miles on the treadmill and lift weights. The worst after-effect has been that I can't taste any food. My taste buds are impaired, so food tastes like cardboard. I'm supposed to eat more than I ever ate before, because there is a tendency to lose weight. It's a real challenge. One of the few foods that penetrate for me is bananas, so I eat a lot of bananas. But the doctors assure me all of this will pass with time. It's a small price to pay for a second life.

I work three to four full days at the office, and then I typically work a day from home. I visit the hospital here weekly for a comprehensive blood workup. The greatest risk post-transplant is infection--fungal, bacterial, viral--and the doctors want to make sure they catch anything at the earliest stage. At the end of the first year, the normal practice is to go back to Seattle, where the doctors essentially repeat everything they did when you came in to see if you get a clean bill of health. If you talk to some of the experts, they would pronounce you cured if the bone marrow is negative for leukemia two years after transplant.

When you first hear you may have leukemia, it puts the fear of God in you instantly. I had never faced anything like this. It's a fairly aggressive disease, and it wasn't so many years ago that it was largely not treatable. I had been going to an internal-medicine physician here for a number of years for an annual physical exam. He does a normal blood workup, and last April he called me and indicated that my white cell count was down. He wasn't overly concerned; he said counts can vary dramatically throughout the day and from person to person. You can't take one count and draw any particular conclusion. But when he repeated the workup a week later and my white count was down further, he thought I should see a hematologist.

I went to the chief of hematology at Henry Ford Hospital in Detroit. She had the same reaction as the internist--not overly concerned--but she felt we ought to do a bone marrow aspiration [a procedure in which a needle is inserted into the hip to withdraw a small amount of bone marrow tissue]. I had her do it right then and there. It takes ten days or so to get the results, and I wanted to understand quickly what was going on. I remember her asking me, 'Do you want to know all the possibilities?' And I said, 'No.' It might have been leukemia or a variety of other blood diseases, but since at that stage it might have been none of them, it served no purpose to speculate until we had good facts in front of us.

On May 26 she called me at my office. She didn't want to talk on the phone, and I knew that was a bad sign. So I went over to the hospital, and that's when she gave me the diagnosis. It was a shock. Overwhelming fear is the first reaction, and it is overwhelming. Your whole life changes before your eyes.

I felt that I owed disclosure to the GM board and to Jack Smith immediately, so I told Jack and board member John Smale the next day. I wanted them to know exactly what had happened and what I knew then, which wasn't much. Just the diagnosis. They and the rest of the board were all very supportive. I also had tremendous support from my family. My wife and I have always been close, but now we're kind of inseparable. My three grown children, one of whom is a physician, were instrumental in getting me into the mode of 'Let's understand this disease. Let's research all the approaches.' Once I got into that mode, it was like being back in my old trial-lawyer days, preparing the case. But it was a rather more important case, since if it wasn't tried well, I was the potential victim.

I had confidence in the diagnosis from Henry Ford, but obviously in these kinds of circumstances you want confirmation. So I immediately set up a meeting at Memorial Sloan-Kettering Cancer Center in New York City. Nobody relies on anyone else's bone marrow aspiration, so they repeated it. I got a lot of holes punched in my backside over the next several months. When the diagnosis was confirmed, the Sloan-Kettering doctors were somewhat surprised by the slowness in development of the disease. Looking back at my medical record, they saw a depressed white count a year earlier. That is not the normal progression of leukemia. With a classic untreated case, you'd probably be dead in three to four weeks.

That week I started an exercise program with treadmill and weights that was even more rigorous than the one I was on. My attitude was, I'm going to do everything known to man if it has even an incrementally positive impact. I walked every day, paid a lot of attention to what I ate, and gave up the occasional glass of wine since I learned that alcohol is a mild bone marrow depressant.

The disease became very distracting mentally. Every moment that you are not absolutely focused on talking to somebody or performing some work function, leukemia fills the void. It's just a constant mental burden. It was very important to my mental health that I do something constructive, not just sit around contemplating my own death. So I pushed myself to stay engaged at work, but to be honest, it's not the same. Your mind goes right back to the disease because, after all, it's the whole ball game.

I took it upon myself to do a lot of research. I got some help from people in the local area, got on the Internet, read what was available, and went to Johns Hopkins to spend a day. I quickly learned that the treatment of leukemia is about half science and half art. But it is a curable disease. There are no guarantees, and the statistics aren't what you'd like them to be, but nevertheless, a not insignificant number of people have been cured.

I was trying to make a judgment about the course of treatment, which was not easy. Sloan-Kettering had a traditional program: chemotherapy in two stages over a period of a couple of months, along with possible radiation and then a transplant. The Fred Hutchinson Cancer Research Center in Seattle had a different program that was relatively new. They called it the direct approach--direct to transplant. You do the chemo in six days, and after a day of rest, you immediately go to a stem-cell transplant. In my case, there was no radiation.

(Stem-cell transplants use donor cells from the bloodstream rather than from the bone marrow. In a process very similar to a blood transfusion, a patient is infused with healthy donor stem cells, which then migrate to the bone marrow, where--if all goes well--they grow into normal blood cells. Because stem cells in the bloodstream are slightly more mature than those in the marrow, people undergoing such a transplant can recover more quickly. Stem-cell donation is also easier for the donor.)

The stem-cell procedure recommended by Fred Hutchinson was typically limited to people age 50 or younger. I was 56, but I was in good physical condition. Whether I had a perfectly matched sibling to donate the stem cells was a key concern of mine in determining which treatment to pursue. It significantly improves the odds for success. I have two brothers--Bill, 58, and Murray, 60--and as it turned out, they were both perfect matches.

Dr. Fred Appelbaum, the physician in charge of my treatment at the Hutch, said the probabilities that their stem-cell transplant would work were 50% to perhaps 60%. Those weren't the kinds of odds I wanted to hear. When I asked him to break them down, he said the first risk is that the chemo gets you, the second is that infection sets in and we can't control it, and another is that the donor cells don't engraft. I thought I could will myself through the chemo, and I knew I would take meticulous care to avoid infection. And it was a huge advantage to have a perfect sibling match because it meant the risk of a graft not taking was substantially reduced.

The toughest thing for me throughout this period was how my son and daughters would handle this if it turned south and I was going to die. I didn't know how I could face them and deal with their reaction to the certainty of my own death. I consciously pushed out of my mind the practical side of what I ought to be doing if I wasn't going to live, like getting my finances in order. The social workers tell you to do that. I listened and mentally rejected it. For me it would have been a sort of admission that I didn't have the kind of will to live that I thought was so important to recovery. I harked back to my football coach in high school, who used to tell us to 'Put losing out of your mind--that's not one of the alternatives here.'

Bill wound up being the donor. We were already very close. We roomed together when I was in law school, and we practiced law together back in North Dakota. He spent a week at the hospital in preparation for the procedure, but he had no ill effects. He just sat in a chair to have his blood taken out, the stem cells removed, and the blood put back in. They ended up with many more stem cells than they needed. They required a minimum of five million cells, and they ended up with nine million plus, so I got a superdose. For me, the actual transplant [on September 2] was a bit of a nonevent. I was pretty ill at the time, and all they do is hang this bag up and open the valve. I was kind of out of it. My recollections of periods in the hospital are pretty sketchy.

The doctors warned me early on not to compare my case to others. You can't assume that if somebody down the hall with leukemia dies, you are going to die. Every case is unique. It affects different people different ways. I kept reminding myself of that, because some people around me, with the same disease and the same treatment protocol, died. Why? I believe part of it is one's attitude about whether this is going to work--and whether you're going to exercise whatever control you can over your body through your mind to make sure it does work.

(After five weeks in the hospital, Pearce was released to a nearby Marriott Residence Inn for two months of outpatient treatment.)

I wanted to be out of the hospital as quickly as possible, and they want you out: The risk of infection can be higher in the hospital than out. My wife was heroic. I couldn't drive and couldn't really go out to eat because of all the special safeguards I needed for food, sanitation, and safety. So she chauffeured, cooked, and nursed me for two months. The nursing that comes with this is not trivial. I was on intravenous systems for nutrients and a variety of medications plus hydration for 20 hours a day, and my wife, who has no medical training, had to operate all the IV pumps. I also had an implanted port in my chest that had to be very carefully cleaned and attended to daily to avoid the risk of infection.

It's infection that often causes the mortality from this disease. I picked up two post-transplant bacterial infections after I was released from the hospital. Fortunately, they were detected early, even before I had symptoms. At the Hutch, doctors monitor bodily fluids multiple times a week. The research center is part of the operating facility, and the doctors have special expertise in doing this early-warning diagnostic workup, which, in my judgment, is one of the reasons they get such good results.

(On December 5, Pearce left Seattle to return to Detroit. Nine days later he was back in his office at General Motors.)

I never disengaged from business except for the five-week hospitalization. Literally from the day after I got out of the hospital and checked in to the Marriott, I got a FedEx package every day filled with work. When you've been through this, your attitude toward work tends to be, I'm going to do the best I can and serve this corporation that has served me so well as long as I'm healthy. The day I can't make the same contributions I was making before, I'll be the first to tell Jack and the board this is not going to work and we need to consider other alternatives, including retirement. I don't anticipate that happening.

When you get into an executive position, the tendency is to focus on your own career. Not that I wasn't trying to do what was in the best interest of GM before, but it was too personalized. I don't have the same view today. I'm more likely now to make a decision based on the fundamental values. I've become a much stronger advocate of teamwork, and I have more compassion for others. Whereas in the past you would have gotten frustrated with somebody when you were trying to explain something to them and they didn't get it--that wouldn't happen now.

There has been a very real transformation in how I think. Even people I didn't care for in the past, I find myself reexamining and looking for the good, and often finding it. This experience focuses your attention on what I would call real value. You're less egocentric, because you realize in a very direct way how the support of others has contributed to your still being around. Your relationship with other people--your family, your friends, your fellow employees--becomes much more important.

I don't think a day passes when I don't think about what happened and the support I got. I consciously plan things out in the future so I can kind of readjust my mindset with respect to life in general. But there is no question that you have a high degree of awareness with every ache and pain that you experience. And it seems every time I pick up a newspaper, I read about someone who has leukemia. It's there all the time.

I have never been one to wear religion on my sleeve, but you do a lot of soul-searching about what your beliefs really are. There is a strong bias to believe in God, because the alternative is a little bleak. It's something you can never logically resolve, but emotionally it provides tremendous support. It gives you confidence that there's something out there working on your behalf beyond pure science. It causes you to focus on your own ethics and your own values more than you ever did, and the importance of those values in the business world. I can't tell you that I spent a lot of time thinking about them before. But I do now."