The present study was initiated to examine the association of dietary habits and chronic diseases, in particular, gastric cancer and cerebro-vascular accidents. Dietary habits were compared between high risk, intermediate risk, and low risk areas. Dietary intake was assessed by questionnaire survey as well as duplicate food study. The questionnaire survey was found very reliable by a reproducibility study interviewing a random sample of about 410 residents in one year interval in Fukuoka. Quantitative intake was assessed for 20 food or food group items. No material difference was noted for most items in different risk areas except for high salt food item. In fact, the high risk area consumed 10 times or more high salt food items than that in low risk areas. Straight line relationship was observed between salt intake from high salt diet and SMRs of gastric cancer and cerebro-vascular accidents. This finding was supported by the duplicate food study, which indicated marked geographical difference in salt consumption but no material difference for carbohydrate, fat, and protein intake. Thus, the present study strongly suggests the importance of salt intake (particularly from high salt diet) in causation of gastric cancer and cerebro-vascular accident.