The IOC president Jacques Rogge has admitted that he expects some athletes to use performance-enhancing drugs at the London Olympics.
"There have been positive cases in each Olympic games since we have started testing," Rogge told BBC Sport.
"To say there will be no positive cases would be naive and misleading. I hope it's the case, but reality tells me that there may be positive cases."
Rogge added: "Everything that is humanly possible has been done in London to minimise doping.
"We hope that it will be the lowest possible number and we do everything we can to protect clean athletes."
The IOC president has suffered recent disappointment in the on-going fight against athletes found guilty of cheating.
Beijing Olympic champion LaShawn Merrit, who was found guilt of doping in 2009 and subsequently served a two-year ban from athletics, won an appeal in October against the International Olympic Committee who were attempting to block him from competing in London 2012.
The Court of Arbitration for Sport (CAS) ruled that preventing the American from competing in the Olympics went beyond the Word Anti-Doping Agency sanctions of a maximum two-year ban and in essence would have been a second punishment for a single offence.
"We are disappointed because we really wanted to have as clean as possible games," reflected Rogge.
"But you know we have created the Court of Arbitration ourselves, so we are going to respect their judgements. Not happy, but we respect the advice."
The British Olympic Association (BOA) have their own hearing with CAS next month when their current bylaw, banning cheats like Dwain Chambers and David Millar from Olympic Games for life, will be challenged.
A recent poll of British athletes suggested that around 90% wanted those who had been caught to remain banned for life.
"This is a decision by lawyers, by jury and we have to respect the law," Rogge told the BBC. "There's no choice. Whether we like it or not is irrelevant.
"I feel comforted by the position of the athletes, which is exactly the same as ours, but there is a respect of the rule of the law."
Rogge was speaking at the Winter Youth Olympics in Innsbruck, also attended by BOA chief executive Andy Hunt.
Commenting on the case, Hunt feels that the BOA had a 'good chance' of success, although it would not be a massive blow if they failed.
"We have actually stood up for clean sport," Hunt told BBC Sport.
"I'm really proud, regardless of the outcome of what we have done in standing up for clean sport."
Rogge's comments were backed on Twitter by women's world marathon record holder Paula Radcliffe, who wrote: "Totally agree with Jaques Rogge's view of dopers and cheats. It is never ok and there are no excuses."
With Team GB's first Olympians of 2012 impressing with three medals in Innsbruck thoughts now turn to London. And Rogge admits that he has been impressed with what he has seen to date.
"I can say clearly that the legacy is there, even before the games begin," he added.
"You have this splendid regeneration of East London, you have new affordable housing with the Olympic village, there is lots of greenery and East London will attract industry with new inhabitants.
Rogge also insisted, despite the on-going uncertainty over the future of the Stadium after the Olympics, that he is certain of a positive outcome.
"In terms of sports venues, most already have a new tenant for after the games, and I am certain the others will in the next six months, so we will not leave white elephants."
Hear more from Jacques Rogge in BBC Radio 5 Live's 'Lord of the Rings' London Calling programme on Thursday (2130 GMT).
Have your say on whether you think drugs cheats should be allowed to compete for Team GB at the London Olympics by adding #OlympicThursday to your tweets.