Participants in this study will receive leuprolide acetate injections once a month for up to 6 months. After 2 months, women whose symptoms have improved will receive a skin patch containing either estrogen or placebo (an inactive substance) and will be asked to take daily suppositories containing either progesterone or placebo. Women whose symptoms of PMS do not respond to leuprolide treatment after 2 months will end the study and be offered other treatment. Participants will be seen by a nurse in the clinic every two weeks and will fill out ratings and have blood drawn to measure hormone levels.