OBJECTIVES: Myasthenia Gravis (MG) is a rare autoimmune disorder affecting neuromuscular communication and voluntary muscle contraction.  The disease is characterized by muscle weakness, exacerbated through movement and alleviated with periods of rest.  Estimated US prevalence is 20/100,000 with an estimated annual health plan cost of $15,675.  Among commercially insured MG patients we assessed characteristics and incremental increases in patient expenditure prior to and following first diagnosis. METHODS: To complete our study we used a large commercial claims database from 2010-2014.  MG patients were identified using ICD-9 code 358.0 and were indexed at first diagnosis. MG patients were evaluated for 1 year (six months prior and 6 months post diagnosis) to assess clinical characteristics, costs and utilization.  Bivariate statistics were used to assess differences between pre and post period costs and utilization. RESULTS: We identified 677 MG patients.  On average male and female patients were of a similar age range. Pre to post period patient visits and costs were statistically significant (p = <0.01). MG patients experienced an incremental increase in total cost ($17,293 – $24,611, p=0.01), in-patient cost ($12,868 – 20,601, p=0.01), office visit cost ($3161 - $4336, p=0.01), and pharmacy cost ($2294 - $3183, p=0.01), from pre to post diagnosis.  Patients diagnosed with MG also had a higher rate of office and pharmacy visits during the post period (12 - 13.83, p=0.01 and 13.29 – 15.34, p=0.01, respectively). CONCLUSIONS: Among MG patients there was an incremental increase in utilization and cost between the 6 months prior to and 6 months post first diagnosis.  This increase was in part due to drug therapy, but must include other clinical factors as the majority of the increase was in inpatient costs.  Further investigation into comparative treatment pathways will hopefully lend insight into the best ways to improve patient quality of life while decreasing costs.