OBJECTIVES:: To report the one-year results of ESWT on CPPS patients and the possible clinical characteristics that may affect its efficacy. PATIENTS & METHODS:: A prospective randomized clinical study between January 2017 and January 2021 on 155 adult patients with chronic pelvic pain syndrome. All patients were initially evaluated with a thorough history and physical examination. Baseline symptoms evaluation of each participant was assessed using NIH-CPSI score, IPSS, VAS, and IIEF-5 score. Patients were randomized into two groups: a verum treatment group and a placebo treatment group. Patients of verum group in the lithotomy position received a perineally applied ESWT treatment once a week for four weeks with 3000 impulses each. Patients of placebo group received the same therapy head of the same device with a layer of air-filled microspheres to absorb the shock waves. The previously mentioned validated scores were reassessed on regular follow-up visits at one, three, six, and 12 months after the completion of ESWT. RESULTS:: A statistically significant improvement was noticed in the mean values of NIH-CPSI, IPSS, VAS, and IIEF-5 of the patients of verum group over the follow-up period with also statistically significant difference between both groups. At the first visit of follow-up after ESWT, 63 (82.8%) patients had ≥6 points decrease in the NIH-CPSI total score, while 13 (17.2%) patients did not. Univariate and multivariate analyses of the clinical characteristics between the responders and non-responders showed that those patients with history of psychological disorders or had higher initial NIH-CPSI score had a significantly lower response rate to ESWT (p = 0.005, 0.02 & p = 0.002, 0.004 respectively). ROC curve of NIH-CPSI score showed that a score of 32 was the cut-off point above which the response to ESWT decreased. CONCLUSION:: ESWT is an effective treatment option for CPPS. Its efficacy remained throughout long-term follow up. High initial NIH-CPSI score and history of psychological problems are significant predictors for it.