During the last year, clinical studies on vitamin D have confirmed the presence of world-wide incidence of vitamin D deficiency. Recently, the investigators detected an incidence of 80% vitamin D deficiency/ insufficiency in patients presenting to our tertiary stone clinic. However, there is no data in the literature regarding the safety of vitamin D replacement in this highly specialized group of patients. Consequently, clinicians are concerned about vitamin D replacement in these patients for fear of increased risk of hypercalciuria and stone formation.