• Vasomotor symptoms prospectively recorded during the first month compared with changes in months one, two and three of the study [ Time Frame: Four months ] [ Designated as safety issue: No ]
• Forearm blood flow by plethysmography prospectively measured before and after three months of therapy [ Time Frame: Four months ] [ Designated as safety issue: No ]

• 1) Vasomotor symptoms prospectively recorded during the first month compared with changes in months one, two and three of the study.
• 2) Forearm blood flow by plethysmography prospectively measured before and after three months of therapy.

• Other hormone-related quality of life measures on the Daily Menopause Diary®, especially self worth, sleep, and energy, recorded during the 4 months of the study [ Time Frame: Four months ] [ Designated as safety issue: No ]
• Changes in two Quality of Life instruments - the Rand SF-36 and the Menopause-specific Quality of Life (MenQoL) questionnaires, measured at baseline and at the end of the study period [ Time Frame: Four months ] [ Designated as safety issue: No ]
• Lipid, blood pressure (BP), waist circumference and weight changes, measured at baseline and at the end of the study period [ Time Frame: Four months ] [ Designated as safety issue: No ]

• 1) Other hormone-related quality of life measures on the Daily Menopause Diary, especially self worth, sleep, and energy, recorded during the 4 months of the study.
• 2) Changes in two Quality of Life instruments- the Rand SF-36 and the Menopause-specific Quality of Life (MenQoL) questionnaires, measured at baseline and at the end of the study period.
• 3) Lipid, BP, waist circumference and weight changes, measured at baseline and at the end of the study period.

The primary purpose of this study is to determine the effects of a full dose (300 mg at hs) of oral micronized progesterone (OMP) on vasomotor symptoms [VMS] (hot flushes/night sweats), on forearm blood flow and on lipid levels and blood pressure in menopausal women without cardiovascular disease and with moderate to severe VMS.

The hypotheses are that progesterone will improve hot flushes, increase endothelium-dependent forearm blood flow and will decrease blood pressure without change in lipid levels.

In this 4-month study, menopausal women are randomized to either placebo or oral micronized progesterone (Prometrium®). Participants maintain a daily diary to keep track of their vasomotor symptoms and other factors. Forearm blood flow will be assessed by venous occlusion plethysmography at baseline and after three months of therapy. Screening tests at baseline to rule out heart disease include measurement of blood pressure and heart rate, electrocardiogram (ECG) and blood tests - fasting blood glucose and lipid profile.

• Drug: Oral Micronized Progesterone (Prometrium®)
• Other: Placebo

• Experimental: Oral micronized progesterone
• Placebo Comparator: Placebo

Inclusion Criteria:

1. Menopausal women (final menstrual period one or more but less than 10 years before)
2. No evidence of vascular disease (normal BP; without diabetes mellitus; normal cholesterol levels and non-smoker for at least a year; and normal ECG.)
3. Moderate to severe VMS during the day and night.

Exclusion Criteria:

1. Any menstruation in the preceding year.
2. History of hysterectomy without ovariectomy unless 60 years of age.
3. Use of ovarian hormone therapy (estrogen, progestin, progesterone or androgen) or selective estrogen receptor modulator (SERM) therapy (raloxifene or tamoxifen) in the preceding six months.
4. Body mass index (BMI) over 35 or less than 20.
5. Mean of several pre-treatment blood pressures over 145/95.
6. Documented abnormal cholesterol; abnormal fasting capillary glucose; abnormal angiogram; ECG or exercise stress tests or a diagnosis of diabetes mellitus; or any history suggestive of angina.