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 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.