The charts of 234 consecutive sexual assault victims age 12 years or greater were reviewed. Substance use by victims and assailants is prevalent. Victims reported substance use immediately preassault in 51% of cases, and substance use by their assailants in 44%. Victim substance use was associated with a trend toward impaired memory for key elements of the assault. Victim knowledge of assailant substance use was associated with acquaintance assaults. Adult and adolescent substance use rates were not significantly different. Adolescents had a higher rate of acquaintance assaults and nongenital injury. Adults had increased rates of memory impairment and weapon involvement.