An unfavorable body fat distribution is associated with many metabolic abnormalities including a high prevalence and incidence of noninsulin dependent diabetes mellitus and decreased high density lipoprotein cholesterol and increased triglyceride levels. One mechanism for the effect of body fat distribution on metabolic variables may be through sex hormones. We examined the relationship of body mass index (BMI), ratio of subscapular-to-triceps skinfold ratio (centrality index) and ratio of waist-to-hip ratio (WHR) to sex hormone binding globulin (SHBG) (an in vivo measure of androgenicity) in 101 postmenopausal Mexican-American and non-Hispanic white women from the San Antonio Heart Study, a population based study of diabetes and cardiovascular disease. SHBG was significantly correlated with BMI (r = -0.440, P less than 0.001), WHR (r = -0.255, P less than 0.01) and centrality index (r = -0.210, P less than 0.05). In a multiple linear regression analysis, SHBG remained significantly associated with BMI (P less than 0.001) and WHR (P less than 0.05) but not with age, ethnicity or centrality index. This work suggests that in postmenopausal women overall adiposity and an unfavorable body fat distribution are associated with increased androgenicity as measured by a lower SHBG concentration. Our finding may help to explain the association of body fat distribution with diabetes and cardiovascular risk factors in older women.