The use of a second generation lithotriptor (Siemens Lithostar) for ESWL treatment of 199 consecutively referred patients with ureteral calculi is evaluated. Follow up data were available in all patients. In 79 patients the calculus was located in the upper third of the ureter, in 43 patients in the middle third and in 77 patients in the lower third of the ureter. In situ ESWL was performed in 187 patients (94%) under local infiltration analgesia, if invasive procedures in conjunction with ESWL were not planned. The overall stone free rates for all patients after 1, 3 and 6 months were 62.3%, 82.4% and 89.9% respectively. The size of the calculus influenced the outcome of treatment, the number of treatments and number of shock waves given. The stone free rates 3 and 6 months after ESWL in patients with upper ureteral calculi were 86.1% and 91.1%; the number of treatments per patient was 1.2. The corresponding rates for patients with mid or lower ureteral calculi were 76.7%, 86.0% (1.0 treatment) and 81.8%, 90.9% (1.2 treatment) respectively. ESWL alone failed to clear calculi in 4 patients with upper ureteral stones, 6 patients with mid-ureteral calculi and 14 patients with lower ureteral calculi. The number of additional procedures post-ESWL was significantly higher among patients with calculi in the lower third of the ureter. It is concluded, that ESWL in situ with a second generation lithotriptor using X-ray localization is an effective and noninvasive method to treat ureteral calculi. In situ ESWL is recommended as first line treatment for ureteral calculi in the upper and mid-thirds.(ABSTRACT TRUNCATED AT 250 WORDS)