Compliance with hormone replacement therapy (HRT) is notoriously low despite ample documentation of clinical efficacy. The two major reasons given by women who discontinue HRT are uterine bleeding and side-effects. The recent development of a controlled and sustained vaginal progesterone gel allowed single daily application and made prolonged use such as for menopause possible. Here we report our clinical experience with two therapeutic options for HRT using natural progesterone administered vaginally. A first group of 69 menopausal women received the sustained release vaginal progesterone gel, Crinone 4% (45 mg daily) from days 1-10 of each calendar month with oestrogens taken continuously. A second group of 67 women received Crinone 4% twice weekly in conjunction with continuous oestrogen therapy. Endometrial thickness was evaluated before and after 6 months of treatment. Histological verification was obtained in all cases of abnormal bleeding. At 6 months, 63 out of 69 (91.9%) women receiving progesterone cyclically experienced predictable withdrawal bleeding. The vast majority, 54 (80.6%) of 67 women receiving Crinone in constant combined association with oestrogen therapy, remained amenorrhoeic throughout 6 months of therapy. All cases of abnormal bleeding were biopsied and no hyperplasia was seen. Our results indicate that both regimens using the sustained release vaginal progesterone gel controlled bleeding in HRT. Combined with the lower incidence of side-effects characteristic of vaginal progesterone, both vaginal progesterone regimens have the potential of improving HRT compliance.