Apart from causing emotional suffering, postnatal depression strains marriage, undermines the mother's confidence, impairs her social functioning and quality of life, and in serious cases contributes to infant abuses, infanticides and suicidal behaviour. Recent studies also show that postnatal depression adversely affects emotional, behavioural and cognitive development of the newborn. In addition, there is growing awareness that depression can occur during pregnancy, and antenatal depression can adversely affect obstetric and neonatal outcomes. Antenatal depressive symptoms are also the strongest predictor of postnatal depression. This paper reviews the epidemiology, clinical presentation, risk factors, prevention and treatment of perinatal depression. The latest development in research and practice related to this condition are also highlighted.