A total of 285 renal units in 248 patients received 424 extracorporeal shock wave lithotripsy (ESWL) treatments with mobile lithotriptors for renal and ureteric stones at Oulu University Hospital. Treatments were given approximately once a month (1-2 days) with 7-10 treatments per day. The overall success at 1-3 months was 88% (74% stone-free). Success with single renal stones was 88% (70% stone-free), that with multiple renal stones 78% (62% stone-free) and that with ureteric stones 93% (89% stone-free). Retrograde manipulation appeared to be a safe and effective treatment for patients with obstructing ureteric stones obliged to wait for the next treatment session. The most serious complication was one perirenal haematoma requiring transfusion. The results compare favourably with those achieved with fixed lithotriptors and prove that mobile lithotriptors are suitable for small centres.