(FORTUNE Magazine) – You exult at the boss's suggestion: "We have a problem in Asia we need you to fix." Sure, you're running at the head of the pack, but your company, like most American enterprises, has discovered the world, and you haven't seen much of it since you backpacked with your girlfriend up to Machu Picchu after college. Visions dance in your head: dining at Singapore's Raffles Hotel with the ghost of Somerset Maugham, exploring Bangkok's water bazaars, browsing through Hong Kong's fetching alleys. The wife and kids will love it, and foreign experience is just the turbothrust you need to catapult into the rarefied ozone of the 39th floor. Right?

Think again. Think really hard. Because while most U.S. corporations will feed your fantasies with seductive spiels about the wonders of overseas experience, once they get you there, experts say, there's a good chance they'll abandon you. Listen to Hal Gregersen, associate professor of international strategy at Brigham Young's Marriott graduate business school: "Never trust your firm to make your assignment a success. They are likely to choose the wrong assignment in the wrong place at the wrong time and set you up for failure before you know it. And when you come back home, most will have forgotten you exist. The move will likely mean career death within the company that sent you."

American firms botch overseas assignments, it seems, because they lack broad, global experience. Gregersen conducted a survey that found that only 15% of the top 50 executives in U.S. corporations had worked abroad, compared with 35% in Europe and 27% in Japan. An anonymous senior line executive at a big American company sums up the situation: "The organization back home...wants to do business in a cookie-cutter way, like, 'Why not do it the same in Vietnam as in South Carolina?' Headquarters has no appreciation for the critical differences, and when you're overseas, you experience tremendous stress trying to educate corporate executives who have no interest in being taught."

Little wonder, then, that a Conference Board study of 152 U.S. companies reveals that 80% of executives posted abroad feel employers do not value their international experience. Upon their return, most repatriates are isolated and ignored. Consider these eye-openers:

--Repatriated foreign execs have a high attrition rate. About 15% leave their companies within a year to 18 months; the figure swells to about 40% after three years.

--Only a third of companies with sizable international operations have a strategy to deal with the problems expatriates encounter, either on assignment or returning home.

--Expectations are out of whack. About 75% of expatriate managers expect the move to benefit their careers, but only 10% receive promotions upon their return. And roughly half don't like their new assignments.

What is going on here? You guessed it: out of sight, out of mind. It may seem petty of your peers to minimize your accomplishments just because you labor in a distant time zone, and to grab every chance to spotlight their own achievements, but, well, that's the way it is. Another problem: Too many international assignments are impulsive efforts to put out a short-term fire. Dispatching a technically proficient person may seem the right solution for the company, but it may be a lousy one for the firefighter.

Does this heavy dose of reality mean that you should wimp out and turn down the chance of a lifetime? Not at all. Advises John Wada, vice president of Prudential Resources Management: "Executives simply need to take active steps to make sure their overseas assignment doesn't become a ticket to nowhere." He and others suggest that expats-to-be insist that bosses tell them exactly what the company expects them to accomplish. Are they to get a plant up and running, or mind the store? Are they expected to groom a replacement from local talent?

More important, you must recognize one brutal truth: You're on your own. The home office may or may not come through, but by milking the assignment--indeed the whole experience--for all it's worth, you will profit. By doing a bang-up job learning about new markets, gaining skills in the language, understanding the culture, and networking until you drop, you will make yourself so valuable that competitors will come crawling with lucrative offers. After all, an executive with a million dollars' worth of training paid for by some parochial chump who chooses to discard him is a thing of value to competitors of keen eye.