PURPOSE: Brachytherapy is an important component of the treatment of gynecologic and prostate cancers, with data supporting its impact on clinical outcomes. Prior data have suggested that brachytherapy tends to be focused at high-volume centers. Medicare reimbursement data can provide an understanding of the distribution of brachytherapy cases among billing providers. The objective of this study is to quantify the distribution of brachytherapy cases and high volume providers. METHODS AND MATERIALS: The Medicare Physician and Other Supplier Public Use File was queried for individual physicians who had performed brachytherapy for more than 10 patients with gynecologic or prostate cancer in the years 2012-2015. Aggregate data were also queried. Trends were identified, and basic summary statistics were tabulated. RESULTS: During the study period, there was an increase in vaginal brachytherapy (3328 unique cases in 2012-4308 in 2015) but a decrease in intrauterine implants, such as tandem placements (1522 in 2012-1307 in 2015) and prostate brachytherapy (8860 in 2012-6527 in 2015). High-volume providers treating more than 10 patients represented a disproportionate number of patients treated, particularly with intra-uterine brachytherapy, representing no more than 1.2% of the active providers in a given year but up to 11.1% of intra-uterine brachytherapy cases. CONCLUSIONS: Among Medicare claims, a small number of providers accounted for a significant proportion of gynecologic and prostate brachytherapy cases, particularly in the case of intrauterine implants. The vast majority of brachytherapy providers perform limited cases in this population. Efforts toward improving access to intrauterine implants in Medicare patients should be a national priority.