The effect of electromagnetic shock waves on the ureter and periureteric soft tissue was investigated in 10 patients who underwent extracorporeal shock wave lithotripsy (ESWL) for lower ureteric stones. Seven patients were males and 3 females, their ages ranged between 15 and 52. The number of shock waves applied varied between 3000 and 6000, at a mean of 19 kV. The patients were examined after their first ESWL. Magnetic resonance imaging (MRI) was performed within 6 hours of treatment by a Magnetom 1 Tesla Unit. No haematoma, fluid collection or abnormality was detected in the periureteric space, muscle or surrounding structures by MRI. Although subcapsular, intra- or perirenal haematomas can be observed in patients with kidney stones treated with ESWL, it appears to be safe for lower ureteric stones.