In an open non-comparative prospective trial of 12 months' duration, we investigated the role of a novel hormone replacement therapy regimen in 40 post-menopausal women who sought hormone replacement therapy. The regimen consisted of continuous administration of 0.625 mg of conjugated equine estrogen coupled with a fixed low-dose of micronized oral progesterone administered for 23 days every calendar month. The regimen was well-tolerated, producing no major side-effects and was effective in relieving menopausal symptoms. The study showed that 40% of the women experienced side-effects and 20% withdrew from the study. Half of the 20% of the women who dropped out did so for reasons not related to treatment. All symptomatic women experienced improvement after the 1st month, and virtually all were asymptomatic by the 3rd month of treatment, persisting until the end of the trial with the average number of hot flushes per day declining from the pretreatment levels by 96%. Amenorrhea was observed in 47% of patients, amenorrhea and minimal vaginal bleeding in 78% but acyclic bleeding was present in 28% of those in whom bleeding was re-established. Endometrial atrophy was induced in the majority of patients and no atypical endometrial hyperplasia was encountered. No significant changes were observed in blood glucose or liver enzymes. The mean percentage changes from baseline for serum cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, low-density lipoproteins (LDL) and LDL/HDL ratio were -6%, +32% (p < 0.001), -16% (p < 0.05), +15% (p < 0.05) and -23% (p < 0.05), respectively. The regimen was clinically effective and its apparent lack of major side-effects, the protective effect on the endometrium, the added advantage of minimal vaginal bleeding and the beneficial effect on lipid/lipoprotein levels, offer an attractive therapy and improved compliance with postmenopausal hormone replacement therapy.