We performed a forensic evaluation of a 16-year-old boy convicted of murdering his 14-year-old girlfriend while he was taking anabolic steroids. Prior to steroid use, he had displayed no features of antisocial personality disorder and no criminal record. Prompted by this index case, we interviewed 133 consecutive male convicts at the same facility where this boy was incarcerated to assess whether steroid use frequently contributed to criminal acts. Two other cases of apparent steroid-induced crimes were found in this cohort, suggesting that steroid use is an uncommon, though occasionally significant, factor in criminal behavior.