To assess the effect of hysterectomy for nonmalignant conditions on symptoms and quality of life and to identify adverse effects 1 year after surgery. The Maine Women's Health Study was a prospective cohort study of 418 women ages 25-50 years undergoing hysterectomy for any nonmalignant condition. Patients recruited from the practices of 63 physicians performing hysterectomy throughout Maine were interviewed at the time of surgery and 3, 6, and 12 months later. Clinical and hospitalization data were obtained from physician reports and from a statewide hospital discharge data base. The primary outcomes of interest were symptom relief, changes in quality of life, and the development of new symptoms or problems during the year following surgery. The most frequent indications for hysterectomy were leiomyomas (35%), abnormal bleeding (22%), and chronic pelvic pain (18%). For these indications, hysterectomy resulted in marked improvements in a range of symptoms, including pelvic pain, urinary symptoms, fatigue, psychological symptoms, and sexual dysfunction. Significant improvements in scores for indices of mental health, general health, and activity were evident at 6 months and sustained at 1 year. New problems after hysterectomy (measured in those free of the symptom preoperatively) included hot flashes (13%), weight gain (12%), depression (8%), and lack of interest in sex (7%). Hysterectomy is highly effective for relief of symptoms associated with common nonmalignant gynecologic conditions. Symptom relief following hysterectomy is associated with a marked improvement in quality of life. New problems are reported after hysterectomy by a limited number of women.