An expose by editors at In Touch Weekly claimed the Two And A Half Men star had been spotted sneaking into the apartment block of lingerie model Angelina Tracy wearing a disguise - including a false moustache.
But the star's spokesman Stan Rosenfield insists Tracy is not Sheen's mistress - she's the sister of someone he is helping as part of his 12 step rehab recovery program.
Rosenfield tells TVGuide.com, "The woman in question is the sister of one of Sheen's campmates, and Sheen was only responding to a 12th step call."
The rep explains the reason for the disguise: "Since Sheen knew he was being followed and how this would look, he wore the moustache in a tongue and cheek disguise gesture."
Sheen entered a rehabilitation centre in February (10) as a "preventative measure" following his Christmas Day (25Dec09) arrest for allegedly attacking his wife. Sheen has pleaded not guilty to third-degree assault, menacing, and criminal mischief and will stand trial in July (10).