Gwynn suffered the injury while fouling off a pitch in Wednesday's game against the Chicago Cubs. The Padres thought he had a sprained wrist, but an examination by a Chicago doctor revealed the break.
Padres manager Bud Black said Gwynn flew back to San Diego on Thursday for evaluation.
Black doesn't know how long Gwynn will be out. Black said Gwynn has made some great game-saving plays with his arm. He's posted a .212 batting average.