STUDY OBJECTIVE: To compare the cardiovascular and metabolic effects of medroxyprogesterone acetate (MPA) with those of conjugated equine estrogen (CEE) as single-hormone therapies in women who underwent hysterectomy with bilateral ovariectomy. DESIGN: Secondary analysis of a 12-month, double-blind, randomized, parallel-therapy trial. SETTING: Four teaching hospitals and one community hospital in Vancouver, Canada. PARTICIPANTS: Thirty-three healthy women who underwent premenopausal hysterectomy with bilateral ovariectomy. INTERVENTION: Subjects received either MPA 10 mg/day (18 women) or CEE 0.6 mg/day (15 women) for 12 months, started immediately after hysterectomy with bilateral ovariectomy. MEASUREMENTS AND MAIN RESULTS: Lipid profiles (high-density lipoprotein cholesterol [HDL], total cholesterol, apolipoprotein B, and triglyceride levels), homeostatic measures (hemoglobin A(1c) and fasting blood glucose level), hormone levels (free and bioavailable testosterone, cortisol, sex hormone-binding globulin [SHBG], and dehydroepiandrosterone sulfate), inflammatory markers (C-reactive protein [CRP] and serum albumin levels), and anthropometric measures (body mass index [BMI], truncal fat, and total body fat) were assessed over the 12-month period. After 12 months, the women assigned to MPA had lesser increases in BMI (p=0.04), triglyceride (p=0.003), HDL (p<0.0005), SHBG (p<0.0005), total testosterone (p=0.003), and CRP values (p=0.01) and higher serum albumin levels (p