The results of extracorporeal lithotripsy on 250 patients with renal and ureteral stones are reported. Stone size varied from less than 1 cm (64%), 1 to 2 cm (31%) to over 2 cm (4%). 51% of patients were treated on an ambulatory basis. Complete fragmentation was obtained in 97% of patients and 78% were free of any demonstrable stone after 90 days. lithotripsy is an effective procedure allowing ambulatory non surgical treatment of urinary stones in many patients.