During a 5-year period 32 children and adolescents 4 to 18 years old underwent 35 extracorporeal shock wave lithotripsy (ESWL*) treatments for 37 calculi. The unmodified Dornier HM3 lithotriptor was used in 21 cases (60%) while the remaining cases were treated with the Siemen Lithostar lithotriptor. The HM3 necessitated general anesthesia in 67% of patients and the Lithostar necessitated intravenous sedation in 86%. The majority of pediatric lithotripsy treatments were performed on an outpatient basis (24) or during an overnight hospital stay (3) while 8 were done on an inpatient basis. Of the 37 stones treated with 1 ESWL session 68% resolved, 19% had residual fragments less than 4 mm., 8% had residual fragments greater than 4 mm. and 5% required an endoscopic procedure for resolution. When success rates by lithotriptor were examined no significant difference between the 2 machines was identified although the HM3 treated larger stones (p = 0.0499). There were no statistical differences in regard to success and the use of stents, patient age or stone location between the 2 lithotriptors. Three patients required adjuvant procedures, and complications and morbidity developed in 2 and 5, respectively. All children or parents were contacted for followup (range 7 to 67 months). One child required ESWL for a new stone while another passed a stone without intervention. Only 1 child with a residual fragment less than 4 mm. became symptomatic but needed no intervention while 1 of 3 with fragments greater than 4 mm. needed intervention. No patients required open or percutaneous intervention.