Women predominate at all ages among patients diagnosed as having primary fibromyalgia. Of 100 patients reviewed, the average age at onset of fibromyalgia was 46. Of 65 patients in whom menopause occurred before diagnosis of fibromyalgia, the average age at menopause was 42, and most of these women had menopause related to surgery and insufficient estrogen therapy. Estrogen deficit is, thus, a prominent promoting factor in the majority of fibromyalgia patients and is likely to have an effect on sleep, mood, and anxiety state. These emotional responses may subsequently be somatized as pain. Therefore, estrogen therapy should be added to the treatment armamentarium for fibromyalgia in selected patients.