The results of primary in situ extracorporeal shock wave lithotripsy of upper ureteral calculi were analyzed retrospectively in 491 eligible patients. The treatment was successful in 371 patients (76%). Degree of obstruction, stone size, localization of stone, history of previous ipsilateral surgery, and body mass index were found to be factors that can influence the outcome of treatment. A scoring system based on these factors has been developed to select the appropriate group of patients for primary in situ extracorporeal shock wave lithotripsy of upper ureteral calculi.