59 children with urolithiasis were seen between 1969 and 1977 (8 1/2 years). Calculi from 50 patients were analyzed by X-ray diffraction. Half of the patients were 0-4 years old, and in this age group males greatly predominated (76%). Calculi in 26 patients were of infectious, and in 15 patients of metabolic origin (cystinuria 7, idiopathic hypercalciuria 5, primary hyperoxaluria 3), whereas 18 were idiopathic. Most infectious stones contained struvite, and most idiopathic stones contained calcium oxalate. An infectious etiology was observed in 55% of the 0-5-year-old children (n = 33), but in only 20% of the 10-16-year-old ones. In contrast, the percentage of idiopathic stones rose from 18% in the youngest to 70% in the oldest age group, although the absolute numbers were similar in all age groups, Childhood urolithiasis in Switzerland is thus primarily observed in young male patients and is usually secondary to a definable cause.