Isoflavone, rich in soy products, have been reported to possess significant antioxidant, estrogenic and tyrosine kinase inhibitory activity. Therefore, soy product or isofllavone intake may prevent against cancer and cardiovascular disease. In addition, the estrogenicity of this substances may be related to the onset of menopause of women. The relationship between soy product and isoflavone intake to subsequent mortality from cancer and cardiovascular diseases was examined in participants in Takayama study. In 1992, a total of 13,355 male and 15,724 female residents in Takayama, Gifu, Japan, aged at least 35 years who were free of cancer, stroke, and ischemic heart disease completed a self-administered questionnaire including demographic characteristics, smoking and drinking habits, diet, exercise, and medical and reproductive histories. Diet including soy and fish intake was assessed by a validated semiquantitative food frequency questionnaire. In men, hazard ratios of the highest compared to the lowest quintile of total soy product intake were 0.89 for cancer mortality and 0.85 for cardiovascular disease mortality. Corresponding figures for women were 0.79 and 0.90, respectively, after controlling for age, total energy and other lifestyle variables. The relationship between soy product intake and the onset of menopause was assessed in women who were premenopausal at the entry into the Takayama study. Soy intake was not associated with the onset of menopause.