We examined the validity and reproducibility of a 44-item food frequency questionnaire used in a baseline survey of the Japan Public Health Center-Based Prospective Study Cohort I conducted in February 1990. Subjects were 94 men and 107 women selected on a voluntary basis among respondents to the baseline survey. Four or five years after the baseline survey, they provided four 7-day diet records during a 1-year period, and then responded to the same questionnaire a second time. The median (range) for energy-adjusted correlation coefficients between 30 nutrients measured by the questionnaire and the diet records was 0.36 (0.06-0.81) for men and 0.37 (0.11-0.52) for women. The median correlation (range) for 17 food groups was 0.30 (0.08-0.75) for men and 0.28 (0.08-0.46) for women. The median correlation (range) for energy-adjusted correlation coefficients between the two questionnaires was 0.24 (0.04-0.69) for men and 0.50 (0.27-0.60) for women for the nutrients, and 0.34 (0.15-0.63) for men and 0.48 (0.18-0.55) for women for the food groups, respectively. The results indicate that this brief food frequency questionnaire provides reasonably valid and reproducible measures of consumption for many nutrients and food groups, and is useful for examining the association between diet and health in the Japanese population.