Background: The success rate of extracorporeal shock wave therapy (ESWT) in treating epicondylitis, plantar fasciitis, rotator cuff tendonitis, Achilles tendonitis, and Jumper knee has been reported to be 60% to 80%. Most published studies have compared focused ESWT at different intensities with local corticosteroid injection (LCI). We only identified a few studies that specifically compared ESWT with LCI in patients with pes anserine bursitis (PAB). This study aimed to compare the effectiveness of ESWT and LCI in patients with PAB. Methods: The present study was a randomized clinical trial. Patients diagnosed with PAB who were referred to the physical medicine and rehabilitation clinic underwent a complete physical examination. They (n = 60 patients) were randomly assigned to the ESWT and LCI groups if they met the study criteria. In the ESWT group, 1 ESWT session was performed weekly for 3 consecutive weeks. In the LCI group, 1 injection was performed under an ultrasonography guide. Pes anserine thickness, pain intensity, and treatment satisfaction were measured with visual analog scale (VAS) and quality of life (Short Form-12). A paired-samples t test was used to compare the results obtained in the pre-and posttests. Analysis of variance for repeated measures was used to detect differences over time. The null hypothesis would not be confirmed if the P value was less than the 0.05 level of significance. Results: Pes anserine thickness and pain intensity decreased significantly during the study in both groups ( P < 0.001). However, the mean difference of pes anserine thickness was more in the LCI group the ESWT group [(-0.6; 95% CI, -1.0 to -0.3) than (-0.1; 95% CI, -0.5, -0.2); P = 0.008]. Also, the mean difference of pain intensity was lower in the ESWT group] than the LCI group [(-2.9; 95% CI, -3.7 to -2.1) (1.0; 95% CI, 0.1to 1.8); P < 0.001]. Patients' quality of life in both groups increased significantly during the study period ( P < 0.001), but the increase in quality of life in patients in the ESWT group (mean difference, 15.3 [95% CI, 10.6-19.9]) was considerably more than in the LCI group (mean difference, -5.3 (95% CI, -10.0 to -0.6). Conclusion: Overall, the results of this study showed that both local corticosteroid injections and extracorporeal shock wave therapy are safe and effective in PAB patients., Competing Interests: The authors declare that they have no competing interests., (© 2023 Iran University of Medical Sciences.)