This study characterized psychotropic medication use among Medicaid-enrolled children and adolescents with autism spectrum disorders by examining trends over time, including length of treatment and polypharmacy using 4 years of administrative claims data from 41 state Medicaid programs (2000-2003). The data set included nearly 3 million children and adolescents who were 17 years or younger. Approximately, 65% of children with autism spectrum disorder received a psychotropic medication. The results indicate an increasing overall trend in the use of psychotropic drugs among children and adolescents with autism spectrum disorders. Among the different classes of psychotropic drugs, antipsychotics were the most common. Increasing trends in polypharmacy were observed both within and between medication classes.