Greater trochanteric pain syndrome (GTPS) is a commonly diagnosed medical issue, yet there are little data assessing the relative morbidity of GTPS. We sought to characterize the morbidity on presentation of GTPS and compare it to that of patients with end-stage hip osteoarthritis awaiting total hip arthroplasty. We hypothesized that patients with GTPS would have morbidity similar to or worse than that of patients with osteoarthritis. This retrospective case-control study examined patient-reported outcome measures of 156 patients with GTPS (193 hips) and 300 patients with hip osteoarthritis before total hip arthroplasty (326 hips). Patients with secondary hip conditions or previous hip surgeries were excluded from the study. Patient-reported outcome measures were analyzed using an equivalence test and two one-sided t tests. Equivalence in mean visual analog scale pain scores between GTPS and osteoarthritis was established with a tolerance margin of ±10. The difference in mean visual analog scale pain scores was 0.35 (95% CI, -0.86 to 0.16; P=.02). The Hip disability and Osteoarthritis Outcome Score Quality of Life was much worse for patients with GTPS, placed well outside of the ±10 tolerance margin, and the difference in mean scores was 1.72 (95% Cl, -2.17 to -1.26; P=.99). Equivalence in mean UCLA Activity scores between GTPS and osteoarthritis was established with a tolerance margin of ±5. The difference in mean UCLA Activity scores was 0.002 (95% CI, -0.45 to 0.43; P<.01). The morbidity and functional limitations of patients with GTPS were similar to those of patients undergoing total hip arthroplasty. GTPS remains a functional problem for patients, and clinicians and researchers should consider GTPS as seriously as hip osteoarthritis. [Orthopedics. 2024;47(4):205-210.].