This study aimed to determine intra-observer and inter-observer reliability of the Mayo Elbow Performance Score (MEPS). Patients undergoing elbow surgery completed a MEPS questionnaire initially and another 2-3 weeks later. During the second interview, patients completed the Oxford Elbow Score (OES) for comparison. Intraclass correlation coefficients (ICC) and Pearson correlation coefficients (PCC) > 0.80 indicated substantial agreement. In 42 patients who had elbow surgery, the average MEPS score initially was 78 (range, 5-100, SD 22.4) and 77 (range, 5-100, SD 21.5) at second interview. The average normalized OES score was 79 (range, 17-100, SD 23.6). The ICC for MEPS scores at the two time points was 0.90, and the PCC between the MEPS and OES scores was 0.87, indicating substantial agreement. The MEPS has strong intra-observer reliability at different time points and strong inter-observer reliability when compared with the OES, validating the MEPS as an outcome measure of elbow surgery. (Journal of Surgical Orthopaedic Advances 31(4):229-232, 2022).