The recent inclusion of research criteria for premenstrual dysphoric disorder in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders should help physicians recognize women with symptoms of irritability, tension, dysphoria, and lability of mood that seriously interfere with their lifestyle. Premenstrual dysphoric disorder can be differentiated from premenstrual syndrome, which is primarily reserved for milder physical symptoms and minor mood changes. The use of criteria from the Diagnostic and Statistical Manual in conjunction with prospective daily charting for at least two menstrual cycles is now accepted as common practice in confirming the diagnosis. Treatment options range from the conservative (lifestyle and stress management) to treatment with psychotropic medications and hormonal or surgical interventions to eliminate ovulation for the more extreme cases. Results from several randomized, placebo-controlled trials have clearly demonstrated that selective serotonin reuptake inhibitors, as well as medical or surgical oophorectomy, are effective in treating premenstrual dysphoric disorder. Taken together, these data indicate that treatment may be accomplished by either eliminating the hormonal trigger or by reversing the sensitivity of the serotonergic system.