Whether all upper ureteral stones must be manipulated before extracorporeal shock wave lithotripsy (ESWL*) is an ongoing controversy. In a prospective trial, symptomatic patients with solitary upper ureteral calculi less than 1 year in duration were alternated between ESWL in situ and pre-ESWL stone manipulation. Pretreatment excretory urograms were assessed for stone size and degree of proximal hydroureteronephrosis, which was graded from zero (no dilatation) to 3 (severe dilatation). Stone manipulation was done with the patient under intravenous sedation and local anesthesia. A total of 4,000 shock waves was given in a single session using Siemens Lithostar Plus, and treatment was repeated on days 4, 15 and 30 if required. The patients were evaluated 3 months after onset of therapy with excretory urogram and urine culture. Seventy patients qualified for the study (group 1-35 in situ and group 2-35 stone manipulation) and were comparable in relation to age and sex, stone size and degree of hydronephrosis. There was no significant difference between the 2 groups regarding the number of sessions (group 1-1.86 +/- 1.2 and group 2-2.03 +/- 1.2) or shock wave requirement (group 1-5,705.8 +/- 3,536.9 and group 2-5,549.1 +/- 3,837.2) for stone fragmentation. The degree of proximal dilatation did not contribute significantly towards the outcome (F ratio 0.675, p = 0.57). A total of 30 patients (85.5%) in group 1 had a satisfactory outcome at 3 months, while 3 (8.5%) had significant residual calculi and 2 stones could not be fragmented. Of the manipulated stones 33 (94%) were successfully cleared, while 2 patients required auxiliary procedures. Ureteroscopy was required in 1 patient for upward migration of the stent. Morbidity in both groups was comparable. We conclude that upper ureteral stones should be treated in situ to avoid the morbidity of manipulation.