Little is known about risk factors for violence among individuals with autism spectrum disorder (ASD). This study uses data from Swedish longitudinal registers for all 422 individuals hospitalized with autistic disorder or Asperger syndrome during 1988-2000 and compares those committing violent or sexual offenses with those who did not. Thirty-one individuals with ASD (7%) were convicted of violent nonsexual crimes and two of sexual offenses. Violent individuals with ASD are more often male and diagnosed with Asperger syndrome rather than autistic disorder. Furthermore, comorbid psychotic and substance use disorders are associated with violent offending. We conclude that violent offending in ASD is related to similar co-occurring psychopathology as previously found among violent individuals without ASD. Although this study does not answer whether ASDs are associated with increased risk of violent offending compared with the general population, careful risk assessment and management may be indicated for some individuals with Asperger syndrome.