Little is known about the use of medical services by children who have autism (ASD). Provide nationally representative data for health service utilization and expenditures of children with ASD. Cross-sectional survey using the Medical Expenditure Panel (MEPS), and National (Hospital) Ambulatory Medical Care Surveys (N(H)AMCS). A total of 80 children with ASD were identified from N(H)AMCS (weighted sample size (wss) 186,281), and 31 (wss 340,158) from MEPS. They had more outpatient visits, physician visits, and medications prescribed than children in general. They spent more time during physician visits than other children. Annual expenses for children with autism spectrum disorder ($6,132) were more than for other children ($860). Children with ASD have a substantial burden of medical illness.