Premenstrual syndrome is primarily diagnosed clinically, with consistent characteristic symptoms occurring in the luteal phase of the menstrual cycle and resolving during menstruation or within the week following it. For a premenstrual dysphoric disorder diagnosis, a patient’s symptoms must substantially interfere with work, school, social activities, or relationships or cause significant distress. Patients should record symptoms for at least two cycles because symptoms can vary from cycle to cycle. A symptom-tracking diary or diagnostic instrument, such as the Daily Record of Severity of Problems (a validated prospective survey tool), can be used to identify the cyclic pattern of symptoms. Selective serotonin reuptake inhibitors are first-line treatment for premenstrual syndrome and premenstrual dysphoric disorder, with rapid onset of improvement; however, adverse effects can limit their use. Cognitive behavior therapy, exercise, acupuncture or acupressure, and the herb Vitex agnus castus may be used to ameliorate premenstrual syndrome and premenstrual dysphoric disorder symptoms. Reassessment for another underlying cause of premenstrual dysphoric disorder symptoms should occur if symptoms are not controlled with medications or other interventions or persist throughout the month.