The effects of pornography, whether violent or non-violent, on sexual aggression have been debated for decades. The current review examines evidence about the influence of pornography on sexual aggression in correlational and experimental studies and in real world violent crime data. Evidence for a causal relationship between exposure to pornography and sexual aggression is slim and may, at certain times, have been exaggerated by politicians, pressure groups and some social scientists. Some of the debate has focused on violent pornography, but evidence of any negative effects is inconsistent, and violent pornography is comparatively rare in the real world. Victimization rates for rape in the United States demonstrate an inverse relationship between pornography consumption and rape rates. Data from other nations have suggested similar relationships. Although these data cannot be used to determine that pornography has a cathartic effect on rape behavior, combined with the weak evidence in support of negative causal hypotheses from the scientific literature, it is concluded that it is time to discard the hypothesis that pornography contributes to increased sexual assault behavior. (C) 2009 Elsevier Ltd. All rights reserved.