Frustrated by years of criticism from the boxing press and fans, he retired upon his second loss of the WBA Title on April 30, 2005 (to James “Lights-Out” Toney). Ruiz un-retired in 10 days, after finding out that James Toney had tested positive for anabolic steroids. The official outcome, a unanimous-decision defeat, was changed to a no-contest; the WBA ordered that Ruiz retain the title. Ruiz then filed a lawsuit against Toney, claiming that he had damaged Ruiz's boxing career (due to Toney's use of illegal steroids before their bout).

On December 17, 2005 he lost his title for the third time — in controversial fashion, — to Nikolay Valuev. Ruiz lost a rematch for the vacant WBA Heavyweight title with Valuev on August 30th, 2008.