Sixty women with climacteric complaints who had not menstruated for at least 1 year were randomly allocated to receive one of four hormonal replacement regimens. All four formulations were administered daily and continuously and each contained 2 mg of micronized oestradiol-17 beta in combination with either norethisterone acetate 1 mg (group A) or 0.5 mg (group B) or megestrol acetate 5 mg (group C) or 2.5 mg (group D). The clinical efficacy was the same although the alleviation of vasomotor symptoms was somewhat slower in those women receiving preparation A. The endometrium was atrophied in nearly all biopsies. Irregular uterine bleeding was almost entirely confined to the earlier phase of the study and was substantially less with the formulation containing 1 mg norethisterone acetate. It is concluded that a continuous oestradiol-progestogen combination can be used for long-term treatment of climacteric complaints in postmenopausal women and that after 4 months the clinical efficacy is the same irrespective of the type and dose of progestogen administered.