Any patient presenting with renal colic requires the taking of a detailed history-- with inquiries about diet and drugs, an examination of the urine, intravenous pyelography and measurement of the calcium concentration in serum and urine. Any stone passed should be analysed. Recurrent stone formation warrants more comprehensive metabolic investigation. The cause of renal calculi in most patients is still not known. When a cause is found, specific treatment can prevent or control stone formation. For the majority in whom no abnormality is detected, various methods of reducing stone formation have been tried but results are disappointing. The most important points in management are the early detection and effective treatment of urinary tract infection or obstruction and the maintenance of a high fluid intake.