Usual prescribing strategies of hormone replacement therapy for postmenopausal women by Los Angeles area gynecologists, both now and 10 years ago, were investigated by a mail survey. Of the 330 gynecologists who responded, estrogen therapy is currently used as a routine by nearly all (95 per cent), for women both with and without a uterus. Over three-fourths of these physicians favor use of 0.625 mg of conjugated equine estrogen. The estrogen is combined with cyclic progestin therapy, usually 10 mg of medroxyprogesterone acetate, by 86 per cent of gynecologists using estrogen for women with a uterus, and by 47 per cent for women without a uterus. Although conjugated equine estrogens were used widely for both groups of patients 10 years ago, a higher dose generally was preferred. Use of progestin therapy was uncommon (less than 20 per cent) for any postmenopausal patients at that time. Although the most common monthly therapeutic regimen for estrogen/progestin therapy is estrogen for days 1-25 and progestin for days 16-25, there is wide variation in prescribing strategies. We present these findings in the context of the probable effects of estrogen/progestin therapy on various chronic disease outcomes.