Fahey confirmed Thursday that more than 30 athletes had been excluded for breaking anti-doping rules over recent months and that the cases include a mixture of positive samples and failure to comply with testing protocols.
He refused to give details of the athletes, sports or nationalities but noted that more than 70 athletes were prevented from competing at the Beijing Olympics for violating anti-doping rules in the similar period leading into the 2008 Summer Games.
"The one thing I will declare: Athletes who seek to cheat at these games, it's more likely they'll be caught than in any other games in our history," Fahey said at a news conference. "The approach that's been taken around the world by national Olympic committees and anti-doping agencies (is) to ensure that they are not going to be embarrassed by having cheats represent their nation."
Fahey said the cases were spread across more than one sport and one country. No athlete with a doping case pending is in Vancouver.
"I don't try to put too much of an emphasis on how good, or how small the number is," he said. "Either way, it indicates we're effective. It's a number I don't think you can ignore. That's why I say it's significant."
About 2,000 drug tests are being carried out during the games, including surprise, out-of-competition checks at training sites and other locations outside the venues.
The IOC on Wednesday said 554 tests 407 urine and 147 blood had been conducted since the opening of the athletes' village last Thursday. None came back positive.
Alexander Derevoyedov, the deputy leader of the Russian anti-doping agency, was quoted as saying by ITAR-Tass news agency that every Russian selected for the Vancouver Olympics had undergone doping testing.
Russian athletes will be under tight scrutiny at the Vancouver Games. More than a half-dozen Russians have been suspended in the past year for using blood-boosting drugs.
Derevoyedov said some athletes have been subjected to five or more tests.
"This is especially the case with risky types of sports biathlon, skiing, skating," he was quoted as saying.
Fahey said increasing cooperation between anti-doping agencies and law enforcement and government authorities around the world, plus work with pharmaceutical companies was improving the effectiveness of drug testing in sports.
"We're getting better. The weaponry that's being used is far more effective," he said. "There was a time when the thought was 'if you blanket test everybody, then you'll pick up some.' Now, with the sharing of information, they're able to target test. Makes us far more effective."
An independent observation panel led by former White House deputy drug czar Scott Burns will monitor the doping tests during the games and, for the first time, have the ability to meet on a daily basis with the IOC to report any concerns about the testing process.
National Hockey League players who compete in Vancouver will have been under WADA's testing regime since last Oct. 15, despite the NHL not being fully compliant with the WADA code.
Fahey said he didn't anticipate more problems from hockey than other Olympic sports federations that are fully compliant.
"I think I can say the ice hockey people have been under scrutiny for several months now," Fahey said. "I'm not concerned about it."