Serum levels of sex hormone binding globulin (SHBG) and testosterone (T) and bone mineral density (BMC) in the non-dominant forearm were determined in 28 postmenopausal women aged 44-62 years. Significant correlations (Spearman's rank correlation test) were found between BMC and SHBG (negative) and between BMC and the T/SHBG index on biologically active androgen (positive). Significant correlations were also found between endometrial pathology (Kruskal-Wallis test; 0 = atrophic, 1 = hyperplasia, 2 = cancer) and SHBG (negative) and the T/SHBG index (positive). It is suggested that SHBG may act as one common denominator in the pathogenesis of postmenopausal osteoporosis and endometrial disease by regulating the levels of unbound, biologically active androgens and estrogens.