International Olympic Committee chief Jacques Rogge says the current doping scandals in cycling and athletics prove that increased drug-testing is working.
Rogge says the fight against drugs must continue
"Events of the recent days are extremely disappointing," said Rogge. "But we should not be discouraged.
"Every test test that catches cheaters demonstrates that increased testing does have an impact."
Tour de France winner Floyd Landis and Olympic 100m champion Justin Gatlin have tested positive for testosterone.
The result of Landis' "B' test will be announced on Saturday at 1000 BST.
Both men have denied cheating but could face long bans.
The IOC president added that it was vital to continue the war against drugs not just for the sake of sport's integrity but also because of the physical dangers of taking performance-enhancing substances.
"We must keep up the fight against doping through strengthened, concerted efforts between governments and the world of sport, not only to test athletes but also to educate young people about the health dangers of doping and the devastating effect it can have on a person's image and career," Rogge said.