The authors experienced 102 cases of percutaneous nephroureterolithotomy (PNL) in the urological clinic at two city hospitals between May, 1984, and July, 1986. Percutaneous access for renal pelvis was performed under interventional ultrasound and the disintegration of stones was mainly performed by an electric drill system. Stones were successfully removed in all the cases, although residual stones were recognized in 16 cases (15.7%). Complications were rather minor and were treated conservatively without open surgery. PNL is a very effective and promising method not only for university hospitals but also for the urological clinic in city hospitals.