This study provides estimates of medical expenditures for a subset of children and adolescents who receive employer-based health insurance and have a medical diagnosis of an autism spectrum disorder (ASD). Data analyzed were from the 2003 MarketScan[R] research databases. Individuals with an ASD had average medical expenditures that exceeded those without an ASD by $4,110-$6,200 per year. On average, medical expenditures for individuals with an ASD were 4.1-6.2 times greater than for those without an ASD. Differences in median expenditures ranged from $2,240 to $3,360 per year with median expenditures 8.4-9.5 times greater. These findings add to a growing body of evidence that children and adolescents with medical diagnoses of an ASD incur elevated medical utilization and costs.