Non-Hispanic Caucasian women between the ages of 18 and 35 years will be recruited to avoid confounding differences as a function of race. PCOS patients will be diagnosed by 1990 NIH criteria. Controls will have regular menstrual cycles at 21 to 35 day intervals, a luteal phase progesterone (P4) level > 3 ng/mL, and no evidence of hirsutism, acne, alopecia, polycystic ovaries or endocrine dysfunction. Exclusion criteria are: present/past history (<5 years) of smoking, cancer, alcohol abuse, drug addiction, severe depression, or post traumatic stress; diabetes; uncontrolled hypertension (≥ 165/100); clinically significant hepatic or renal disease, or other major medical illness; signs or symptoms of infection; recent (within 30 days) use of an experimental device; recent (within 6 months) use of androgens, anabolic steroids or non-steroidal anti-inflammatory drugs; recent (within 3 months) use of hormonal agents (including birth control pills or insulin sensitizers); use of the drug warfarin.