OBJECTIVES: This study estimated health care resource utilization (HCRU) and medical costs in both pediatric and adult Medicaid populations, comparing epilepsy-related costs with overall costs. METHODS: A retrospective analysis was conducted using Thomson Reuters’ Medicaid claims data from 13 states (2005-2009). Epilepsy patients were identified through ICD-9 code 345.xx and 780.39 . Annual HCRU and medical costs (in 2009 dollars) in adult (>=18 years) and pediatric patients (2-17 years) were estimated separately. HCRU was considered as epilepsy-related if it was associated with ICD-9 code of 345.xx or 780.39, or was an anti-epileptic drug. RESULTS: A total of 75,111 patients were identified with epilepsy, with 31,484 pediatric (mean age 8.8 years) and 43,627 adult (mean age 40.4 years). Annually, a pediatric patient with epilepsy incurred 0.23 hospital admissions (0.13 epilepsy-related), 1.31 ER visits (0.38 epilepsy-related), 6.12 physician office visits (1.25 epilepsy-related), 3.25 outpatient hospital visits (0.91 epilepsy-related), 27.17 other outpatient visits (1.62 epilepsy-related), 22.3 prescriptions (3.96 epilepsy-related). Among adult patients, average HCRU was 0.90 hospital admissions (0.43 epilepsy-related), 3.52 ER visits (0.66 epilepsy-related), 10.26 physician office visits (1.62 epilepsy-related), 7.44 outpatient hospital visits (1.07 epilepsy-related), 58.69 other outpatient visits (2.65 epilepsy-related), 71.43 prescriptions (10.1 epilepsy-related). Direct medical costs per patient were $10,669 (18.4% epilepsy-related) for a pediatric patient and $29,886 (17.7% epilepsy-related) for an adult patient. Overall direct medical costs associated with active epilepsy in the identified Medicaid population were $293 million ($62 million for pediatric and $231 million for adult). CONCLUSIONS: Non-epilepsy related HCRU and direct medical costs dominated HCRU and direct medical costs in Medicaid patients with epilepsy, indicating that substantial comorbidities are associated with epilepsy patients in the Medicaid population. Adult patients had higher HCRU and direct medical costs compared to pediatric patients, which may be related to likely differences in the types of epilepsy experienced by children and adults.