Epidemiologic studies based on quantitative estimation of food and nutrient intake have been limited inJapan. We evaluated validity and reproducibility of a personal computer (PC)-assisted dietary interview usedin the Fukuoka Colorectal Cancer Study. The subjects were 28 participants as controls in a population-basedcase-control study. Four 7-day diet records were kept during a period from July 2001 to May 2002, and the PCassisteddietary interview was administered before and after the diet records (May to July 2001 and July toSeptember 2002). Intakes of total energy, 26 nutrients, and 19 food groups were estimated. Of 26 Pearsoncorrelation coefficients for energy-adjusted nutrients, 18 for the first interview and 19 for the second interviewwere 0.40 or greater, with the highest correlation for saturated fat in the first interview (0.72) and vitamin C inthe second interview (0.60). Validity scores were fairly high for most of the food groups with an exceptionallylow correlation for potatoes (0.19 for the first and 0.13 for the second interview). Reproducibility was good formost nutrients and foods; but low correlation was noted for Vitamin D and nuts/seeds. Reproducibility wasmodest for fish and fish products, beef and pork, and processed meat. The PC-assisted dietary interview wasfairly valid and reproducible regarding most of the nutrients and food groups. Validity and reproducibility ofmeat and fish intakes were probably attenuated because of the episode of bovine spongiform encephalopathy inSeptember 2001.