Deontay Wilder believes “a lot” of boxers are turning to doping and insists he knows the doctors issuing performance-enhancing drugs.
WBC world heavyweight champion Wilder, 33, says fighters “think they are smart” and “try to play the system”.
Wilder told newsmen, “I think a lot of sports have a problem with doping, not just boxing. It’s all over.”
American Wilder has faced criticism for discussing killing an opponent as he prepares to face Dominic Breazeale.
The pair face off at the Barclays Center in Brooklyn on Saturday and Wilder has drawn scrutiny for saying he is “trying to get a body on my record”.
But his comments on doping follow the high-profile drug test failure of American Jarrell Miller, who was set to face IBF, WBO and WBA world heavyweight champion Anthony Joshua on 1 June.
Breazeale, 33, has lost one of his 21 fights – a seventh-round knockout by Britain’s unified world heavyweight champion Joshua in 2016.
The American will look to inflict a first defeat on Wilder – who has 40 wins and a draw in 41 fights – in a bout which will be covered in a live text by BBC Sport in the early hours of Sunday morning.