To clarify the relationship between the westernization of dietary habits and the changes of mortality from breast and ovarian cancers in Japan, correlation analyses were performed using data from the Vital Statistics and National Nutritional Survey Reports. With increasing population size of the areas, the age-adjusted death rates (AADRs) for both types of cancer increased together with the per capita intakes of fat, animal protein and western-style foods such as butter & margarine, cheese, ham & sausage and dairy products. The association of the AADRs with the population size was strong after the age group of 45-54 years in breast cancer, and became stronger as the age increased in ovarian cancer. The association of the AADRs with western-style foods was also observed in the correlation analyses among the 12 geographical districts in Japan. From chronological correlation analyses, the correlation coefficients for some nutrients and foods in breast cancer were highest when the "time-lag" between the foods/nutrients intake and the cancer mortality was assumed to be around 10 years. The results of the present study suggest that an increase of western-style fat-rich foods such as butter & margarine, cheese, bread and ham & sausage among Japanese might be associated with the recent increase of AADRs for breast cancer and ovarian cancers in Japan.