Prospective randomized trials with respect to stone prophylaxis deal mainly with idiopathic calcium stone disease. There is a lot of evidence that alkali citrate, thiazides and allopurinol are effective in many patients. However, appropriate patient selection seems to be crucial. Alkali citrate and allopurinol have proven clinical efficacy in patients with hypocitraturia or hyperuricosuria, respectively. The correct method of patient selection for treatment with thiazides remains unclear. Despite the lack of prospective randomized trials, it is generally accepted that the first steps in the prophylaxis of idiopathic calcium stone disease are high fluid intake and a sensible diet.