Between 1983 and 1988, 15 patients (18 kidneys) underwent percutaneous nephrolithotomy at this unit for calculi in horseshoe kidneys. A standard 1-stage percutaneous access technique with minor modifications was used. In situ disintegration with ultrasound or electrohydraulic lithotripsy was necessary in 15 moieties (83.3%) and nephrostomy drainage was required in 12 (66.7%). Percutaneous access was not a problem and there were minimal perioperative problems. Blood transfusion was required postoperatively in 2 patients. A total of 14 kidneys (77.8%) were rendered free of stone with percutaneous nephrolithotomy alone and 2 kidneys were left with asymptomatic stone fragments of 2 mm. or less. Another 2 kidneys became free of stone after extracorporeal shock wave lithotripsy, thus giving an over-all stone clearance rate of 88.8%. We conclude that percutaneous nephrolithotomy is an acceptable treatment for stones in horseshoe kidneys and it is the treatment of choice for patients in whom imaging is difficult or impossible.