Women's mental health can be compromised during reproductive life, but to date there has been relatively little specific investigation of the links between multiple births and perinatal psychiatric illness. There has been more comprehensive examination of some of the psychological sequelae of multiple gestations and births, but many of the studies have small samples and are descriptive in nature. Most of the literature is drawn from investigations of the psychological aspects of multiple births following assisted conception. Current conceptualizations of the determinants of maternal perinatal mental health, with particular reference to multiple gestations and births are discussed and implications for clinical practice suggested. Overall there is evidence that women with multiple gestation and multiple births may be at elevated risk for pregnancy anxiety, postpartum depression and complicated grief reactions. Much less is currently known about the associations between multiple birth and either maternity blues or postpartum psychosis. The relationships between personal or family psychiatric history, past experience of childhood abuse, intimate partner intimidation and psychological adjustment to multiple births are not known. The interactions between multiple births, operative delivery, prematurity, neonatal illness and separation of mother and infant as contributing factors to maternal postpartum mental health are not known. There is very limited evidence about the psychological functioning of fathers of multiple infants. Routine antenatal, intrapartum and postnatal health care for women with multiple infants needs to take into account the additional psychological demands they face.