Sex hormone binding globulin (SHBG) concentration was measured in serum samples from 2077 premenopausal and 901 naturally postmenopausal women who had no history of disease or of recent drug use likely to affect SHBG. Current users of oral contraceptives (OCs) and of oestrogen replacement therapy had higher mean SHBG values than non-current users. Both premenopausal and postmenopausal women who had previously used OCs had a lower mean SHBG concentration than never users of OCs. Previous use of oestrogen replacement therapy was not related to SHBG.