Research into etiology of marital aggression has focused primarily on psychosocial, political, and cultural factors, to the exclusion of physiological influences. Fifty-three partner abusive men, 45 maritally satisfied, and 32 maritally discordant, nonviolent men were evaluated for past history of head injury, by a physician who was not informed of group membership and aggression history. Logistic regressions confirmed that head injury was a significant predictor of being a battered. The implications of these findings for both marital aggression and post-head injury rehabilitation are discussed.