Many women have menstrual symptoms, but relatively few have severe PMS. PMS is a well-defined premenstrual cluster of predominantly affective symptoms that disrupt a woman's daily functioning. PMS is diagnosed with prospective charting of symptoms and should be differentiated from nondisruptive menstrual symptoms, major affective disorders, and other common medical and gynecologic conditions. Most women with PMS can be helped. The serotonin reuptake inhibitors are becoming the first line of therapy for PMS because they are effective, easily tolerated, and free of major side effects. There is also evidence supporting the role of other antidepressants, anxiolytics, and GnRH agonists in the treatment of PMS. Although increasing control of one's life, promoting a healthy diet, the avoidance of salt and caffeine, vitamin supplementation, and exercise have not been proved as effective treatment for PMS, they should be promoted for their obvious general health benefits. No one treatment fits the heterogeneous PMS population. A trial of medication should be continued for two or three menstrual cycles with appropriate dose adjustments. If relief is not sufficient, other agents or other treatments should be initiated.