Many U.S. Olympic athletes say failing a drug test is the one of the biggest fears they will have at the Salt Lake City Games which open next Friday.

About 40 percent of U.S. Olympic athletes say they fear flunking drug tests even if they do not use banned substances. They are concerned about the ability to catch real drug cheaters.

The findings were contained in results of a survey of more than 700 athletes released Thursday by the U.S. Anti-Doping Agency, which is responsible for drug testing and education in American sports programs. The survey, conducted by the agency several months ago, found 91 percent of the U.S. athletes said they would not take banned drugs even if they knew a major competitor was using them.

The survey also revealed that 81 percent of the athletes would not resort to drugs even if such use would guarantee a gold medal. Among athletes responding, 84 percent said they did not use performance-enhancing substances because they considered it cheating, while 79 percent acknowledged potential health risks.

But a significant number of U.S. athletes also doubted the reliability of the drug testing system. They fear they will be caught by false positive test results. Testing officials say they will address those fears through drug-education plans for athletes, coaches, trainers and parents.