Background: Previous studies reported mixed findings about racial and ethnic disparities in overall survival (OS) in mCRPC. This study describes OS by race and ethnicity among men with mCRPC in the US Medicare population. Methods: Men newly diagnosed with mCRPC were identified in Medicare fee-for-service claims during 1/1/2014–6/30/2019. Adult men were required to have a diagnosis of prostate cancer, metastasis diagnosis, castration-resistance using a published claims-based algorithm, and continuous insurance coverage for ≥1 year before and ≥6 months after index mCRPC diagnosis unless patients died. OS from mCRPC diagnosis and from start of first-line (1L) therapy for mCRPC for White (W), Black (B), Hispanic (H), and Asian (A) men were estimated using Kaplan-Meier analysis and Cox proportional hazards models adjusting for patient characteristics and 1L mCRPC therapy type or no treatment. Results: Among 14,780 men with mCRPC in this study, 75% were W, 14% were B, 6% were H, 3% were A, and 3% were of other or unknown race. Mean age at mCRPC diagnosis was 76 years among W men; B men had similar age while H and A men were slightly older than W men (Table). B, H, and A men had higher Quan-Charlson Comorbidity Index (CCI) than W men. Median follow-up after mCRPC diagnosis was 17 months. Similar proportions of W, H and A men (78%, 78%, and 79%, respectively) and lower proportion of B men (75%) initiated 1L life-prolonging therapy after mCRPC diagnosis. Among treated men, higher proportions of B, H, and A men (71%, 74%, and 73%, respectively) initiated 1L therapy with novel hormonal therapy than W men (64%). Median OS after mCRPC diagnosis was 26.0, 22.3, 22.9, and 24.2 months among W, B, H, and A men, respectively. Median OS after initiation of 1L mCRPC therapy was 23.8, 21.1, 19.9, and 24.1 months among W, B, H, and A men, respectively. After adjusting for patient characteristics and 1L treatment, OS was not different for B and H men relative to W men, while A men had lower risk of death. (Table). Conclusions: This study found no statistically significant differences in overall survival in mCRPC for B and H men and lower risk of death for A men relative to W men after adjusting for patient characteristics and treatment in the US Medicare population.