OBJECTIVES: To determine and compare: 1) the incremental total costs (direct and indirect) for children (age 3-17 years) with and without ADHD; and 2) differences in the incremental direct costs for children with and without ADHD with respect to age groups (infants, 0-5; children, 6-11; and adolescents, 12-17 years); while controlling for covariates. METHODS: The 2011 Medical Expenditure Panel Survey (MEPS) was the data source for the study. The sample consists of all children (age 0-17 years) with a diagnosis of ADHD (ICD9-code=314) (Group-I) and without a diagnosis of ADHD (Group-II). The incremental total cost of ADHD comprised of direct expenditures (prescribed medications, inpatient, ambulatory, and emergency department care), and the indirect costs (parents’ loss of productivity due to absence from school by children). A two-part model with logistic regression and a generalized linear model was used to estimate the incremental costs of ADHD while controlling for age, gender, race, Charlson co-morbidity index, family income, health insurance, usual source of care, area, and region. SAS 9.3 and STATA 12.0 were used for statistical analyses. RESULTS: