Six studies providing information on 2,704 patients were included into a retrospective analysis. The incidence of spontaneous passage relating both stone size and location was determined from these collated studies. The rate of spontaneous passage for stones smaller than 4 mm was 38% compared to 1.2% for those larger than 6 mm, irrespective of their position in the ureter at the time of presentation. Calculi discovered in the distal third of the ureter had a spontaneous passage rate of 45%, compared with the mid third of 22%, and the proximal third of 12%. Two thirds of all stones which passed did so within 4 weeks after the onset of symptoms. These data from the literature were compared to the treatment modalities applied for the last 100 consecutive patients treated with the diagnosis of ureteral stone at UCSF. 42% of the stones were found in the proximal, 13% in the mid and 45% in the distal third of the ureter. Treatment modalities included ureteroscopic stone extraction (36), ESWL (31) and watchful waiting for stone passage (30). Oral litholysis was performed in 2 cases and percutaneous removal of a proximal stone in 1. No calculus larger than 6 mm passed spontaneously. The passage rate from the proximal ureter was 18%, from the mid ureter 15%, and 38% from the distal ureter disregarding the size of the stones. The rate of complications reached 20% when symptoms exceeded 4 weeks in duration compared to 7% in patients with symptoms lasting less than 4 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)