The Storz Modulith SL20 is a third-generation lithotripter which was installed in our hospital in March 1991. The aim of this paper is to evaluate our results in the management of renal calculi using this machine. We report our experience in the treatment of the first 215 renal units (118 renal and 83 ureteric) in 190 patients with a minimum follow-up period of three months. Success for renal stones was defined as stone-free or with insignificant residual fragments of less than 4 mm in size post therapy. Success for ureteric stones was defined as stone-free after therapy. The success rate for renal calculi was 88% and for ureteric calculi 71%. The mean number of sessions to achieve these results for renal calculi was 1.6 and for ureteric calculi 1.4. Of the failures, only 1.9% required open surgery whilst the remainder were dealt with using minimally invasive procedures like intracorporeal laser lithotripsy. There was no mortality in our series. Complications occurred in four patients, who required hospitalisation for renal colic (n = 1), urinary tract infection (n = 1) and obstructive uropathy (n = 2).