Premenstrual syndrome (PMS) is a combination of physical and emotional symptoms that many women get after ovulation and before the start of their menstrual period. It is thought to be caused by a dramatic drop in estrogen and progesterone levels if you are not pregnant. Premenstrual Dysphoric Disorder (PMDD) is a condition much like PMS in that it happens in the week or 2 prior to the onset of period when hormone levels begin to plunge after ovulation. PMDD causes more severe symptoms than PMS, including severe depression, irritability, and tension that can trigger problems with work or personal relationships. This chapter describes the etiology, symptoms, and pharmacological and non-pharmacological management of PMS and PMDD. SSRI’s are first line for PMD/PMDD and can be taken just during from ovulation to menstruation or continuously. The non-pharmacological approaches include diet, exercise, and sleep.