An open prospective multicentric trial has been conducted over 6 months in 241 postmenopausal volunteers. One-hundred forty-one women had an intact uterus. All patients received a fixed peroral combination of conjugated estrogens CE (1.25 mg per day from day 1 to day 21) and medrogestone (5 mg per day from day 12 to day 21) followed by 7 days without substitution (day 22 to day 28). After 3 months of treatment, the managing physician could, according to the patient's clinical response, reduce the dosage of CE to 0.625 mg daily. This dose reduction took place in 79 patients (38.9%). The trial was designed to study efficacy, compliance and side-effects of this combination. Of the patients 68.9% showed a very good, 27.7% a good and 1.9% a satisfactory improvement of their preexisting subjective complaints. Of the patients 28.6% suffered from minor side-effects leading to drop-outs in 7.8% of the cases. Of the women participating in the study 92.2% completed the trial without deviation from the treatment scheme. No serious complications have been noted. After 6 months of treatment, a regular bleeding pattern has been observed in 71.5% of the 144 non-hysterectomized women, an irregular pattern in 9.7% and amenorrhoea in 18.8%. Total cholesterol showed no change, whereas HDL rose significantly from 1.58 to 1.72 mmol/l (P < 0.01) resulting in a drop of Total-Cholesterol-HDL-Ratio of -8.8% (P < 0.01). LDL decreased from 3.71 +/- 1.56 to 3.45 +/- 1.39 (P < 0.05). Considering the two patient groups with and without estrogen reduction after 3 months, HDL increase was significant in both groups but was dose dependent. The HDL increase compared to the initial value was 5.7% with 0.625 mg CE and +10.8% with 1.25 mg CE, respectively. The fixed peroral combination of CE and medrogestone tested was effective, easy to administer and safe. The bleeding pattern observed was mostly regular. The pattern of serum lipids changed favorably in a significant way. Therefore, the use of this new peroral estrogen/progestin combination can be recommended for routine substitution in postmenopausal women.