The prevalence of idiopathic nephrolithiasis is increasing in rich countries. Dietary manipulation could contribute to the prevention of both its first appearance and the recurrence of the disease. The target of dietary treatment is to decrease the "urinary lithogenic risk factors" such as low urine volume, hypercalciuria, hyperoxaluria, hyperuricosuria, hyperphosphaturia, hypocitraturia, hypomagnesuria and excessively alkaline or acid urinary pH. Due to the lack of randomized controlled trials focused on this problem, there is not ample evidence to confidently recommend dietary changes. Despite this, numerous recent and past experiences support modification of diet as having a primary role in the prevention of nephrolithiasis. In particular, it is recommended to limit animal protein and salt intake, to consume milk and derivatives in amounts corresponding to calcium intake of about 1200 mg/day and to assume fiber (40 g/day), vegetables and fruit daily avoiding foods with high oxalate content. Furthermore, vitamin C intake not exceeding 1500 mg/day plays a protective role as well as avoiding vitamin B6 deficiency and abstaining, if possible, from vitamin D supplements. Lastly, it is recommended to drink enough water to bring the urinary volume up to at least 2 L/day and, as much as possible, to use fresh or frozen products rather than prepacked or precooked foods which are often too rich in sodium chloride.