Hypercalciuria has become a significant clinical focus both for pediatricians and for pediatric nephrologists after it was found that increased urinary calcium excretion is the most common abnormality in children with nonglomerular hematuria and with nephrolithiasis. The question of long-term implications of hypercalciuria in growing children, regardless of the underlying cause, remains unanswered. Whether dietary or pharmacologic therapy is warranted in children with hypercalciuria is controversial. One of the proposed consequences of hypercalciuria is nephrocalcinosis. With the availability of increasingly sensitive, noninvasive imaging techniques, nephrocalcinosis is being recognized more frequently. In some instances, concern about the risk and progression of nephrocalcinosis is provoking reevaluation of well-established metabolic therapies. New urinary inhibitors of crystal formation and aggregation have recently been identified. As the basic pathogenesis of nephrocalcinosis becomes clearer, clinical therapies will become more specific and effective.