ImportancePrevious studies have demonstrated racial and ethnic inequities in medical student assessments, awards, and faculty promotions at academic medical centers. Few data exist about similar racial and ethnic disparities at the level of graduate medical education.ObjectiveTo examine the association between race and ethnicity and performance assessments among a national cohort of internal medicine residents.Design, Setting, and ParticipantsThis retrospective cohort study evaluated assessments of performance for 9026 internal medicine residents from the graduating classes of 2016 and 2017 at Accreditation Council of Graduate Medical Education (ACGME)–accredited internal medicine residency programs in the US. Analyses were conducted between July 1, 2020, and June 31, 2022.Main Outcomes and MeasuresThe primary outcome was midyear and year-end total ACGME Milestone scores for underrepresented in medicine (URiM [Hispanic only; non-Hispanic American Indian, Alaska Native, or Native Hawaiian/Pacific Islander only; or non-Hispanic Black/African American]) and Asian residents compared with White residents as determined by their Clinical Competency Committees and residency program directors. Differences in scores between Asian and URiM residents compared with White residents were also compared for each of the 6 competency domains as supportive outcomes.ResultsThe study cohort included 9026 residents from 305 internal medicine residency programs. Of these residents, 3994 (44.2%) were female, 3258 (36.1%) were Asian, 1216 (13.5%) were URiM, and 4552 (50.4%) were White. In the fully adjusted model, no difference was found in the initial midyear total Milestone scores between URiM and White residents, but there was a difference between Asian and White residents, which favored White residents (mean [SD] difference in scores for Asian residents: −1.27 [0.38]; P < .001). In the second year of training, White residents received increasingly higher scores relative to URiM and Asian residents. These racial disparities peaked in postgraduate year (PGY) 2 (mean [SD] difference in scores for URiM residents, −2.54 [0.38]; P < .001; mean [SD] difference in scores for Asian residents, −1.9 [0.27]; P < .001). By the final year 3 assessment, the gap between White and Asian and URiM residents’ scores narrowed, and no racial or ethnic differences were found. Trends in racial and ethnic differences among the 6 competency domains mirrored total Milestone scores, with differences peaking in PGY2 and then decreasing in PGY3 such that parity in assessment was reached in all competency domains by the end of training.Conclusions and RelevanceIn this cohort study, URiM and Asian internal medicine residents received lower ratings on performance assessments than their White peers during the first and second years of training, which may reflect racial bias in assessment. This disparity in assessment may limit opportunities for physicians from minoritized racial and ethnic groups and hinder physician workforce diversity.