Objectives: The knowledge of the natural history (i.e. the course of the disease without metaphylaxis is the base for establishing rational guidelines for metaphylaxis in urolithiasis. Methods: This review is based on a Medline(TM) Search (1966-1999) and the proceedings of the Bonn-Vienna and European symposia on urolithiasis. Only 31 references were sufficient for the purpose of this review. Results: in idiopathic ca Ici um stone disease, stone frequency without metaphylaxis is 0.10-0.15 stones per patient per year. The average recurrence rate is 30-40%. Recurrence rate increases with age and observation time. Risk for recurrence is highest during the first 4 years after the first stone episode. More than 50% of all recurrent stone formers have only one recurrence during their lives. 10% of recurrent stone formers have more than 3 recurrences. Risk factors for recurrence are: male sex, multiple and lower calyx stones, early onset, familiar history, complications after stone removal. Metabolic evaluation is a poor predictor of the risk for recurrence. Conclusions: Renunciation of metaphylaxis is justified in first stone formers with idiopathic calcium oxalate and apatite stones. All patients, however, should be advised to increase their fluid intake. Copyright (C) 2000 S. Karger AG, Basel.