All 24 fighters who participated on Dec. 29's UFC 155 card in Las Vegas were tested for steroids and drugs of abuse and passed the screenings.
The results were released by the Nevada state athletic commission's executive director Keith Kizer, who distributed them to media outlets including MMA Fighting on Friday.
The event, which was the last on the UFC's 2012 calendar, took place at the MGM Grand Garden Arena in Las Vegas.
The show was headlined by a UFC heavyweight championship match pitting Junior dos Santos against Cain Velasquez. In a rematch of their November 2011 bout, Velasquez won in a lopsided unanimous decision to avenge his only career defeat and regain the title.
The event also featured the return of Chris Leben, who had twice tested positive for banned substances, and was coming off a one-year ban for a positive screening for the prohibited substances oxycodone and oxymorphone. Leben ultimately fell in a unanimous decision to the debuting Derek Brunson.