(FORTUNE Magazine) – In some companies they have an acronym for it, like TFO (for Too F---ing Old). If you're over 50, or even over 45, and looking for a job, the attitude is all too familiar, and the fact that age discrimination is illegal doesn't matter. A new survey of senior executives by ExecuNet (www.execunet.com), a career networking and job-search service, found that 82% consider age bias a "serious problem" in today's workplace, up from 78% in 2001. A startling 94% of those managers, almost all in their 40s and 50s, said that they believed their age had resulted in their being cut out of the running for a particular job, although it was usually impossible to prove. Strange, when you consider how rapidly the U.S. population is aging: According to the Census Bureau, the proportion of Americans who are at least 55 years old will grow by 46.6% between now and 2010, making them 38% of the population and by far the fastest-growing segment of the workforce.

So what gives? Do baby-boomers discriminate against each other? Maybe. Even a fiftysomething manager might prefer to sign up someone younger. The ExecuNet study (available in its entirety at www.execunet.com/age.cfm) also suggests that, in a kind of vicious cycle, such large numbers of 50-plus managers have already been put out to pasture through layoffs and early-retirement programs that the only people left to make hiring decisions in many companies are, well, young enough to think 50 is older than dirt. But the main culprit, it seems, is the rotten job market. Says ExecuNet CEO Dave Opton: "When job seekers outnumber the available jobs, employers use age as one way to quickly screen out candidates."

Getting past that brick wall isn't easy. Don't bother pretending to be younger. "Forget about the superficial stuff like cosmetic surgery and dyeing your hair," says David Carpe, a principal at Clew (www.clew.us), a human resources consulting firm. "You'll just look desperate." Instead, he urges well-seasoned job hunters to stay physically fit, energetic, and upbeat. Exercise, eat right, and get enough sleep. "I see people in their 70s who are vibrant, energetic, and in great demand," says executive coach Tom Massey in Oklahoma City. "I also see 'old' 50-year-olds who are burnt out." You can decide which you're going to be.

The biggest advantage you can give yourself, says Dave Opton, is research. "With any kind of bias, whether it's age, sex, race, or what-have-you, there is a spectrum," he says. "Some people are totally open-minded, while at the other end of the range are those who are so prejudiced that you will never change their minds. Most are somewhere in the middle. If you go into an interview with detailed research showing that you understand the business, the challenges it faces, and what problems need solving, interviewers will tend to look past your age and focus on your ideas." He adds, "I believe people in their 40s and 50s have a strong work ethic that younger workers often lack--and your willingness to do thoughtful, in-depth research will demonstrate it." Worth a try.