ObjectiveTo evaluate the relative prevalence of 8 rheumatic and musculoskeletal diseases (RMDs) across racial and ethnic groups within the National Patient-Centered Clinical Research Network (PCORnet).MethodsElectronic health records from participating PCORnet institutions and systems from January 1, 2013, to December 31, 2018, were used to identify adult patients with ≥ 2 diagnosis codes for rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), osteoporosis (OP), granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA), giant cell arteritis (GCA), and Takayasu arteritis (TAK). Among those with race and ethnicity data available, we compared prevalence of RMDs by race and ethnicity.ResultsData from 28,059,546 patients were available for analysis. RA was more common in patients who were American Indian or Alaska Native vs White, with a prevalence of 11.57 vs 10.11/1000 (odds ratio [OR] 1.15, 95% CI 1.09-1.22). SLE was more common in patients who were Black or African American (6.73/1000), American Indian or Alaska Native (3.82/1000), and Asian (3.39/1000) vs White (2.80/1000; OR 2.43, 95% CI 2.39-2.46; OR 1.39, 95% CI 1.25-1.53; OR 1.26, 95% CI 1.21-1.31, respectively). SLE was more common in patients who were Hispanic vs non-Hispanic (prevalence 3.93 vs 3.45/1000, OR 1.14, 95% CI 1.12-1.16). TAK was more common in patients who were Asian vs White (prevalence 0.05 vs 0.04/1000, OR 1.43, 95% CI 1.00-2.03). OP, RA, and the vasculitides were all more common in patients who were White vs Black or African American.ConclusionThese data provide important information on the prevalence of RMDs by race and ethnicity in the United States. PCORnet can be used as a reliable data source to study RMDs within a large representative population.