Objective: To evaluate routinely applicable criteria to predict fragmentation of renal calculi by extracorporeal shock wave lithotripsy (ESWL). Patients and Methods: Two hundred and two consecutive patients (121 men, 81 women), median age 48 (range 19-81) years, were treated with the original Dornier HM-3 lithotriptor at a single stone center. Inclusion criteria were: solitary stones, 10-30 mm in greatest diameter, located in renal pelvis or calyces. Based on plain radiographs, the calculi were classified according to their size, form, location, density (compared to the 12th rib), structure and surface. Furthermore, age of the patient, gender and body mass index were also considered for evaluation. Disintegration was documented on day 1 after ESWL by plain Xray. A multivariate regression analysis was applied to at I preoperative parameters, based on the dual variable stone free versus residual fragments. Results: The overall disintegration rate was 95.5%; 42 patients (20.8%) were completely stone free, and 151 patients (74.7%) had clinically insignificant residual fragments (5 mm or smaller). 14.9% of men and 29.6% of women were stone free (p = 0.01). All other parameters did not reach statistical significance. Conclusions: The disintegration rate of the HM-3 is excellent for kidney stones; women did significantly better than men. However, because of this high disintegration rate, a much larger series would be necessary to define possible differences between preinterventional parameters, if there were any at all. Copyright (C) 2001 S. Karger AG, Basel.