There have been numerous case studies and press reports of individuals committing acts of extreme violence while taking large doses of Anabolic-Androgenic Steroids (AAS). However, research using psychometric measures of aggression has tended to use small numbers of subjects which makes generalizing results difficult. In the current study the State Trait Anger Expression Inventory (STAXI) was administered to 50 AAS users and 40 non AAS-using control subjects. Subjects also underwent a semistructured interview focusing on AAS's effects on levels of aggression. Results showed that AAS users reported being significantly less in control of their aggression than controls. The semi-structured interview findings showed that elevations in aggression due to AAS use were reported by 60 per cent of AAS users. However, these elevations appeared more related to irritability and bad temper than acts of physical violence. The study also found that more AAS users than controls had worked as doormen/bouncers. This highlights the issue of whether AAS use causes aggression or whether aggressive individuals are attracted to AAS use. Future research should investigate this question.