Premenstrual syndrome (PMS) or the more severe and debilitating form premenstrual dysphoric disorder (PMDD) affects a large proportion of menstruating women. PMS and PMDD are associated with a cyclical recurrence of mood and behavioural and physical symptoms in the late luteal menstrual phase, which significantly interferes with a woman’s physical and psychological well-being. The aetiology of these disorders is unclear, but research suggests involvement of altered neurotransmitter systems and increased sensitivity to gonadal hormone fluctuations. Due to the complexity of the disorder, there is no single treatment that is successful for all women; however, various treatments aimed at regulating neurotransmitter systems and suppressing gonadal steroids have been efficacious. This chapter will provide an updated review on diagnosis, prevalence, morbidity, risk factors, and evidence-based treatments that have been effective in treating the symptoms of PMDD.