Turkmenistan's Tejen Tejenov on Thursday became the first medallist at the Hangzhou Asian Games to fail a doping test, officials said, and fifth athlete in all.
The 30-year-old, who came second in the heavyweight 90kg category of kurash, an ancient form of wrestling, tested positive for anabolic steroids, the International Testing Agency said.
He has been provisionally suspended and is in danger of being stripped of his silver medal.
"The athlete has been informed of the case and has been provisionally suspended with immediate effect," said the ITA, which handles some areas of doping control at the Games.
"He has the right to request the analysis of the B-sample."
Tejenov won silver behind Uzbek winner Mukhsin Khismomiddinov on September 30 and was tested the same day.
Doping results generally take several days to come through.
Uzbek cyclist Aleksey Fomovskiy, Philippine mountain-bike rider Ariana Evangelista, Saudi distance runner Mohammed Yousef Alasiri and Afghan boxer Mohammad Khaibar Nooristani have also failed drugs tests in Hangzhou.
They have also been provisionally suspended.
The Games end on Sunday.