Electromagnetic shock waves are sufficiently powerful to break ureteral stones in situ under X-ray control. Fifty consecutive patients were treated for ureteral stones (20 lombar, 4 iliac, 26 pelvic); the average length was 7.5 mm; 48 times in one session, twice in two sessions. At 6 months, 98% of these patients were stone-free (with IVP control) and one patient was lost to follow-up.