This experiment examined the effect of video-game violence on cooperative decision making. Participants (N= 48) were randomly assigned to play either a violent or a nonviolent version of the video game Doom (TM) in dyads. Following the video-game task, participants were separated and given an opportunity to choose to cooperate with their partner for mutual gain, withdraw from the interaction, or exploit their partner for their own benefit. Participants in the violent condition were significantly more likely to choose to exploit their partners than participants in the nonviolent condition. These findings suggest that playing violent video games may undermine prosocial motivation and promote exploitive behavior in social interactions.