Objective: To test the effects of media violence exposure on blood pressure, negative affect, hostile social information processing, uncooperative behavior, and attitudes toward health risk behaviors among young men varying in lifetime violence exposure within the home and community. Design: Experimental laboratory study. Setting: University campus situated within an urban environment. Participants: One hundred male undergraduates aged 18 to 21 years. Intervention: Men who had previously reported differing amounts of lifetime home and community violence were randomly assigned to play The Simpsons: Hit and Run (low-violence condition) or Grand Theft Auto III (high-violence condition). Main Outcome Measures: Systolic and diastolic blood pressure; negative affect; hostile social information processing; uncooperative behavior; and permissive attitudes toward violence, alcohol use, marijuana use, and sexual activity without condom use. Results: Men randomly assigned to play Grand Theft Auto III exhibited greater increases in diastolic blood pressure from a baseline rest period to game play, greater negative affect, more permissive attitudes toward using alcohol and marijuana, and more uncooperative behavior in comparison with men randomly assigned to play The Simpsons. Only among participants with greater exposure to home and community violence, play of Grand Theft Auto III led to elevated systolic blood pressure in comparison with play of The Simpsons (mean, 13 vs 5 mm Hg). Conclusions: Media violence exposure may play a role in the development of negative attitudes and behaviors related to health. Although youth growing up in violent homes and communities may become more physiologically aroused by media violence exposure, all youth appear to be at risk for potentially negative outcomes.