Five premenopausal women were followed with measurements of androgens, oestrogens, gonadotrophins and sex hormone binding globulin (SHBG) after ovariectomy for benign disease. After a period of 6 weeks without treatment the women were treated with oestradiol 4 mg daily for 8 weeks, oestradiol 4 mg plus norethisterone acetate (NETA) 2 mg daily for 8 weeks and finally oestradiol 4 mg daily for another 8 weeks. The levels of androgens did not change during the various periods. As usual during oral treatment oestrone and oestrone sulphate were elevated while oestradiol levels were in the pre-operative range during treatment, regardless of the addition of NETA. SHBG was elevated during oestrogen-only treatment, while addition of NETA normalized the concentration of SHBG. In the combined NETA period concentrations of free oestradiol and non-SHBG-bound oestradiol were significantly elevated, and gonadotrophins returned to premenopausal levels, in contrast to the high levels in the oestrogen-only periods. Using oral oestrogen therapy it may be preferable to add a progestagen rather than elevate the oestrogen dose. Progestagen will result in more free oestradiol and give greater relief of symptoms, but the potentially harmful effect of progestagens on blood lipids must be considered.