Low pressure generator has been developed mainly to reduce pain and kidney injury while at the same time maintain an equally effective stone-free rate. Our experience in using Modified HM-3 Dornier lithotripter to treat urinary tract stones has given an average of stone-free rate (58.88%) quite similar to what the conventional one can give. Compared with the conventional intervention, the modified one might increase by 52.07% (2281 vs 1500 pulses) in the average frequency of shock wave and by 26.52% (38.40 vs 30.35 minutes) in average operation time. However, low pressure may contribute to less complications and overall smoother procedure under oral analgesic use.