Are male pro boxers allowed to wear shirts or must they fight topless?
I know that they usually don't wear shirts, but are shirts actually prohibited by the WBA, WBC, WBO, or IBF?
The Association of Boxing Commissions rules prohibits shirts for their boxers.
1.17 Contestants may wear only boots and shorts approved by the Inspector and the Referee. Male Boxers must be stripped to the waist. Female Boxers will wear above the waist a singlet under which such protective cover as sports bra with breast protector inserts or a one piece breast protector must be worn.
The WBA do not seem to have any rules on apparel (although they do address bandaging and protective cups). Nothing from WBC or WBO. I don't see anything in the IBF rules about shirts, although their Bout Rules do require the color of the fighter's trunks to be noted.
In general, male boxers do not wear shirts because they provide a way to be grabbed, they can reduce freedom of movement, and they decrease heat dissipation.