Between 150 and 200 Asian Games athletes have already been tested for doping, the Olympic Council of Asia said on Monday, with no positive results so far.
Speaking at an anti-doping press conference on the second full day of the Games in the Chinese city of Hangzhou, the OCA said dope-testing was "gaining momentum" at the event.
Mani Jegathesan, an adviser to the OCA anti-doping committee, warned that drug cheats would be rooted out.
Up to 200 athletes have been tested so far, he said, but any positive results will take several days to come through.
"Every athlete participating in these Games must understand that they could be picked at any time," Jegathesan warned.
"That is the best step to ensuring we have a clean event."
There are about 12,000 athletes at the 19th Asian Games, more competitors than the Olympics, and Jegathesan admitted it would be impossible to test them all.
Instead, they will prioritise, including picking out those who break world or Asian records.