INTRODUCTION: Little is known about the costs of managing rare diseases, and comprehensive healthcare costs have not been reported for myasthenia gravis (MG). We evaluated the direct costs and healthcare resource utilization in insured MG patients. METHODS: Costs were obtained from 1288 patients diagnosed with MG who were identified from the Accordant Health Services nationwide medical and pharmacy claims database. RESULTS: Average annual medical/pharmacy claims costs per patient were: $6710/$1196 (age 0-19 years); $17,949/$19,573 (20-39 years); $15,112/$12,498 (40-64 years); and $12,597/$8,089 (65(+) years). Total annual MG-related pharmacy costs were $9.4 million; IVIg accounted for 85% of all MG-related pharmacy costs. Non-steroidal immunosuppressives, cholinesterase inhibitors, and corticosteroids accounted for 9.3%, 5.7%, and 0.2% of pharmacy costs, respectively. CONCLUSIONS: Costs related to the treatment of MG are higher than those of many other chronic neurological diseases. A large percentage of costs result from IVIg use, particularly among a subset of patients who receive frequent IVIg infusions.