Premenstrual syndrome is defined as recurrent moderate psychological and physical symptoms that occur during the luteal phase of menses and resolve with menstruation. It affects 20 to 32 percent of premenopausal women. Women with premenstrual dysphoric disorder experience affective or somatic symptoms that cause severe dysfunction in social or occupational realms. The disorder affects 3 to 8 percent of premenopausal women. Proposed etiologies include increased sensitivity to normal cycling levels of estrogen and progesterone, increased aldosterone and plasma renin activity, and neurotransmitter abnormalities, particularly serotonin. The Daily Record of Severity of Problems is one tool with which women may self-report the presence and severity of premenstrual symptoms that correlate with the criteria for premenstrual dysphoric disorder in the Diagnostic and Statistical Manual of Mental Disorders, 4th ed., text revision. Symptom relief is the goal for treatment of premenstrual syndrome and premenstrual dysphoric disorder. There is limited evidence to support the use of calcium, vitamin D, and vitamin B6 supplementation, and insufficient evidence to support cognitive behavior therapy. Serotonergic antidepressants (citalopram, escitalopram, fluoxetine, sertraline, venlafaxine) are first-line pharmacologic therapy.