Objectives. To determine the optimal frequency of extracorporeal shock wave lithotripsy of urolithiasis, in terms of efficacy and duration, by comparing three different shock wave frequencies. Methods. A total of 170 patients between the ages of 18 and 69 years with radiopaque kidney stones were included in the study. The patients were randomly separated into three groups. Group 1 (56 patients) received 120 shock waves per minute, group 2 (57 patients) received 90 shock waves per minute, and group 3 (57 patients) received 60 shock waves per minute. The duration, analgesic or sedative requirement, and complications were recorded for each treatment. All patients were evaluated in terms of successful treatment by radiography of the kidneys, ureters, and bladder and abdominal ultrasonography 10 days after the single-session therapy. Results. No statistically significant difference was observed in patients according to age, sex, stone size, side, composition, location in the kidney, total energy level, or number of shocks. The successful therapy rate in groups 2 and 3 was prominently greater compared with that for group 1, and the difference was statistically significant (P = 0.032 between groups 1 and 2 and P = 0.015 between groups 1 and 3). The analgesic or sedative requirement in groups 2 and 3 was lower than that in group 1, and the difference was statistically significant (P = 0.003 between groups 1 and 2 and P = 0.001 between groups 1 and 3). The duration was longer in group 3 than in groups 1 and 2, and the difference was statistically significant (P = 0.000 between groups 1 and 3 and P = 0.009 between groups 2 and 3). Conclusions. The results of our study have shown that the optimal frequency during extracorporeal shock wave lithotripsy is 90 shock waves per minute in terms of duration, efficacy, and analgesic and sedative requirement at the same total energy level. © 2005 Elsevier Inc.