Postnatal depression is a common condition that may have a significant negative impact on both infant and mother, often remaining undiagnosed and untreated. Development of effective means of detection, prevention and treatment of postnatal depression is a major health challenge. The objective of this article is to critically review pharmacological, psychological and psychosocial approaches of prevention and treatment for postnatal depression. There is little evidence of short-term success for preventive interventions and some evidence of short-term success for treatment interventions. No preventive or therapeutic studies, however, have provided evidence for long-term success. There is a need for future research into the prevention and treatment of postnatal depression including the assessment of long-term effects on the child's development as well as feasibility in relation to cost-effectiveness.