During 5 years, between 1978 and 1982, 40 patients (22 male, 18 female) aged 1 to 17 years presented with kidney stones at the Erlangen University Children's Hospital. Stone analysis showed calcium oxalate in 61%, calcium phosphate respectively magnesiumammonium phosphate in 33% and cystine in 6%. Calcium phosphate/ magnesiumammonium phosphate stone bearers were most frequently found in the first 5 years of age and showed more often urinary tract malformations, staghorn renal calculi, urinary tract infections and a higher urinary pH. Calcium oxalate stone bearers were more frequently found in patients of school age and had more often relatives with nephrolithiasis. In the group of calcium oxalate stones hypercalciuria, hyperoxaluria and hyperuricosuria were most frequently observed.