Normal cyclic menstruation involves a delicate concert of hormonal events, characterized by midcycle ovulation and, if no pregnancy is achieved, menstrual flow. Women's health--and especially their reproductive health and fertility--may be affected by abnormalities in cyclicity or in menstruation. A number of valuable modes of therapy have recently become available. Abnormal cyclicity may be caused by decreased estrogen levels (from exercise, smoking, or eating disorders). Small ovulation induction pumps, which deliver minute physiologic concentrations of gonadotropin-releasing hormone (GnRH) around the clock, can be used for safe and successful treatment. Increased estrogen levels may also affect cyclicity, and may be suppressed with new GnRH antagonists or stimulated to cyclicity with pure follicle-stimulating hormone. Abnormal menstruation may be caused by intrauterine scarring or fibroids. Outpatient hysteroscopic surgery may successfully and conservatively be used to treat these problems. Today, even women who have been born without a uterus or who have undergone hysterectomy may have a child through a host uterus program. This combines in vitro fertilization of the husband's sperm with his wife's egg with transfer of the embryo into a host who is capable of carrying the pregnancy. Our potential to improve women's reproductive health continues to expand, as some of the recent developments described above for treating abnormalities of cyclicity or menstruation attest.