Between January 1985 and October 1991, 54 patients with calculi in a solitary kidney were treated by ESWL using the Dornier HM-3 lithotriptor. The mean age of the patients was 53.9 years (range 24-77 years). In 51.9% of the cases the stones measured > 1 cm in diameter, in 42.6% between 0.4 and 1 cm, and in 5.5% < 0.4 cm in diameter. In 39 of the 54 patients (72.2%) the calculi could be disintegrated by a single ESWL treatment. In 12 patients (22.2%) 2 ESWL treatments were necessary, and another 3 patients (5.6%) needed 3 ESWL treatments. In 6 cases (11.1%) percutaneous nephrostomy (PCN) was needed, and in 8 other patients ureteric stents were inserted prior to ESWL because of obstruction of the upper urinary tract, causing impending urosepsis in 8 of these 14 cases. Following ESWL, PCN was performed in 4 cases (7.4%) and a ureteric stent was inserted in 2 patients (3.7%) because of urinary obstruction. At discharge from the hospital 15 of the 54 patients (27.8%) were stone-free and 34 patients (63.0%) had small residual fragments of < 0.4 cm in diameter. One year after treatment, 42 patients could be evaluated at a control examination. 37 of these 42 patients (88.1%) were stone-free and 3 patients (7.1%) showed residual fragments of < 0.4 cm. In conclusion, our results demonstrate that, if there is no ureteric obstruction present prior to ESWL, the majority of patients with a solitary kidney do not present extraordinary problems and do not need auxiliary procedures.