The daily consumption of various nutrients and the daily habits of 241 male stone formers were investigated. The patients (especially uric acid stone formers and hypercalciuric (greater than or equal to 300 mg/day) calcium stone formers) ingested much more total protein and animal protein than healthy Japanese. However, the amount of ingested calcium by the patients (470 mg) was less than that of healthy subjects (553 mg) and did not reach the level of the daily nutritive requirement (600 mg). The amount of ingested nutrients during the evening meal by the patients was about 50% of the daily amount with over 60% of the daily animal protein being ingested at dinner. This tendency was high in subjects who were in their 20's to 40's. The interval from dinner until retiring in the patients was not different from that of healthy males, but it was under 4 hours in over 50% of those in their 30's and 40's in both groups. From these results, we thought that a rapid change in nutritional status and dietary style in the short period after World War II had strongly affected the incidence of renal stone disease in Japan. Therefore, we have established the following general guidelines: 1) increased fluid intake, especially after dinner, 2) correct and avoid unbalanced diet (the diet should include all kinds of food, with vegetables being eaten at every meal and avoidance of an excessive intake of meat), 3) eat three meals a day and avoid an excessive intake at dinner, and 4) extend the interval from dinner until retiring. By following these individual dietary guidelines, the 5-year stone recurrence rate and the stone episode rate decreased remarkably in the period of not only outpatient visits but also in the period when the outpatient visits were discontinued. From these results, we conclude that individual dietary management should be the primary measure for the prophylaxis of renal stone disease in Japan.