OBJECTIVES: To determine the relative contribution of intra- and inter-individual variation in the consumption of foods and nutrients. DESIGN: Cross-sectional study. SETTING: Two rural towns in the Miyagi Prefecture, a northeastern part of Japan. SUBJECTS: Fifty-nine men and sixty women. METHODS: Four 3-d food records were collected in four seasons within a year. The total variance in the consumption of 15 nutrient variables and 16 food groups was partitioned by analysis of variance into its inter- and intra-individual components, separately for men and women. RESULTS: The ratio of the intra- to inter-individual variance was larger than unity in 87% (13/15) of the nutrients in men and 100% (15/15) in women. The ratio was largest for retinol (52.9 in men and infinity in women) and smallest for carbohydrates (0.8 in men and 1.5 in women). The ratio was larger than unity in 88% (14/16) of the food groups in men and 94% (15/16) in women, which was smallest for cereals (0.6 in men and 0.9 in women). CONCLUSIONS: The results were consistent with previous western studies in that intra-individual variation was generally larger than inter-individual variation for the consumption of both foods and nutrients. SPONSORSHIP: This study was supported in part by Grants-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture (09470106) and by Health Sciences Research Grants for Research on Health Services (H10-25) from the Ministry of Health and Welfare in Japan.