We determined sex-hormone binding globulin (SHBG) and corticosteroid binding globulin (CBG) by radioimmunoassay of serum samples from a group of 253 women, who were 54 or 60 years old when first studied in 1968-69. The SHBG concentration was highly significantly and inversely related to body mass, body mass index, waist-to-hip circumference ratio, and serum triglyceride concentration; CBG concentration was inversely related to body mass and body mass index. The concentration of neither protein was related to whether or not the subject smoked. Decrease in the concentration of SHBG, but not of CBG, was a significant risk factor for 12-year overall mortality. The plot of the 12-year incidence of myocardial infarction vs SHBG concentration was U-shaped. We recommend that SHBG be included when serum androgens or estrogens are being evaluated as risk factors for cardiovascular disease and death.