Pharmacological interventions are frequently used to treat commonly associated mental health and behavioural issues in individuals with autism spectrum disorders (ASD). Despite high rates of psychotropic drug use documented in children with ASD, very few studies have examined medication profiles, side effects, and rates of polypharmacy in adolescents and adults with ASD. To address this, we examined medication profiles and predictors of polypharmacy among 142 adults with ASD who had experienced a psychiatric crisis. Of the 142 adults sampled, 91 (64.1%) were prescribed at least 1 psychotropic medication and 41 (28.9%) were taking 3 or more psychotropic medications. Variables associated with and predictive of polypharmacy included history of aggression, residence, and psychiatric support. Adults with ASD are a highly medicated population and polypharmacy is a significant concern in this vulnerable group of individuals. (Contains 7 tables.)