Progestogen treatment is associated with a number of subjective symptoms. In the present study, 148 healthy post-menopausal women suffering from mild climacteric symptoms were randomly allocated to 12 weeks of treatment with (a) 2 mg oestradiol valerate combined with cyproterone acetate, medroxyprogesterone acetate or levonorgestrel; (b) 1.5 mg 17 beta-oestradiol combined with desogestrel; or (c) placebo. Climacteric symptoms, Kupperman index scores and potential adverse progestogen effects were recorded before treatment and three times per month during therapy. All the hormone regimens had a rapid effect, reducing the severity of climacteric symptoms to about 30% of the baseline values (P less than 0.001) within one month. Hot flushes were reduced in severity and/or frequency by 76 100% within 3 months (P less than 0.001). The regimens which included hydroxyprogesterone derivatives produced a transient increase in breast tenderness. Other recorded potential adverse progestogen effects showed no significant changes during the study. We concluded that the addition of progestogens (whether 19-nortestosterone or hydroxyprogesterone derivatives) does not produce significant side effects during combined hormone replacement therapy.