Thirty-five adolescent subjects from a psychiatric facility participated in a study to determine the effects of listening to heavy metal versus rock music on affect shifts and to determine the relationship between music preference and shifts in affect. In addition, primary diagnoses of the subjects were examined in relation to type of music and subsequent affect shifts. Short-term fluctuations in mood were measured before and after music listening, and music preference was assessed with a rating sheet completed during testing. Overall, no significant pre-post differences were found in the affect shifts of the subjects; however, when grouped according to music preference, those subjects preferring heavy metal music after listening to heavy metal music were found to have significant increases in positive affect. The affect of those preferring mainstream rock did not show a parallel shift after listening to rock music. Subjects' primary diagnoses had no significant bearing on shifts in affect after music listening.