Alex Rodriguez tested positive for a banned stimulant in 2006, the first year Major League Baseball tested for the substance, according to two people with knowledge of the drug-testing results.
The positive test raises questions about statements Rodriguez has made in connection with the use of performance-enhancing drugs.
The people spoke on condition of anonymity; drug-testing results are supposed to remain secret.
A spokesman for Rodriguez said Sunday that Rodriguez had never tested positive for the substance.
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Rodriguez was not publicly identified at the time for the test because under Major League Baseball’s drug testing program, players are not sanctioned the first time they test positive for that substance. A second positive test is publicly disclosed, and the player is suspended for 25 games.
The recent suspension of Rodriguez — the New York Yankees third baseman who began his career with the Seattle Mariners — by Bud Selig, the commissioner of baseball, was not related to his use of stimulants. Rodriguez was suspended for 211 games by Major League Baseball, which thinks he used steroids and other banned drugs. He has appealed the suspension and is waging a public-relations war on the tactics the sport used in its investigation of him.