The policy seems to be working before Beijing, with dozens of athletes from different sports and countries nabbed recently for doping offenses.
The busts are the result of a global program of increased out-of-competition screenings, including targeted testing of suspected dopers, to weed out as many dirty athletes as possible from the 10,000 competitors coming to Beijing for the Aug. 8-24 Games.
"Our message has been: 'Leave the cheats at home. Catch them before they leave your shores,' " said John Fahey, the president of the World Anti-Doping Agency. "We're seeing the dividends."
An unofficial count by The Associated Press found at least 45 athletes from 11 countries have been ruled out of the Olympics in the past few weeks for drug violations. The list includes athletes in track and field, swimming, wrestling, weightlifting, boxing, fencing and cycling.
"You'll probably find the number is even higher," said David Howman, the director general of the WADA. "Many countries now have realized that the shame that falls upon them from a positive test at the Games themselves is something they want to avoid, so they put their athletes through rigorous testing before they leave."
Surprise out-of-competition controls are considered the most effective way of catching dopers, though many can still slip through the net by evading the system or using undetectable substances.
The International Olympic Committee and WADA have worked with international sports federations to step up the number of pre-Games tests.
"This is not a trend," IOC president Jacques Rogge said. "It's a deliberate policy."
A total of 4,500 tests will be carried out throughout the Olympic period, up from 3,600 in Athens four years ago. The top five finishers and two randomly selected athletes in each event will be tested for the usual menu of steroids, stimulants, blood boosters and other performance-enhancers.
The Athens Games produced a record 26 doping cases. Based on the increase in testing in Beijing, Rogge has predicted there could be 30 to 40 positives this time.