Medication use was examined in 286 adolescents and adults with ASD over a 4.5 year period. A total of 70% were taking a psychotropic or non-psychotropic medication at the beginning of the study. Both the number of psychotropic and non-psychotropic medications taken, and the proportion of individuals taking these medications, increased significantly over the study period, with 81% taking at least one medication 4.5 years later. Our findings suggested a high likelihood of staying medicated over time. Thus, adolescents and adults with ASD are a highly and increasingly medicated population.