We screened 1647 randomly selected Turkish primary school children to detect the prevalence of hypercalciuria. Ninety-seven children had hypercalciuria, with a prevalence of 5.88 percent. Mean Uca/Ucr ratio was 0.135 +/- 0.108; mean Uca/Ucr value for girls was 0.139 and for boys 0.130 (p > 0.05). Mean Uca/Ucr of boys with hypercalciuria was 0.341 +/- 0.09 and of girls 0.327 +/- 0.08 (p > 0.05). Of these 97 children all investigations could be completed in only 40 and these cases were considered to be idiopathic. Twelve children (21%) had a family history of consanguinity and 17 (29.8%) of renal stones. The relation between blood parathormone and Uca/Ucr ratio was not statistically important (p > 0.05).