Postnatal depression (PND) is recognised as a common maternal health problem, but little evidence examines PND among refugee, asylum seeker and immigrant women in developed country settings. This review aimed to identify the rates of PND and highlight common risk factors among this group of women. An iterative and dynamic literature search was conducted across ten databases to identify published articles on PND among immigrant, asylum-seeking and refugee women in developed country settings. Medical Subject Headings (MeSH) and 'free text' search terms, as well as thesaurus terms, acronyms and truncation were used where appropriate. Findings suggest that PND may affect up to 42% of migrant women, compared to around 10-15% of native-born women. Common risk factors for PND among migrant women include history of stressful life events, lack of social support and cultural factors. With a growing number of babies born to immigrant mothers, greater awareness of PND among this group is needed in order to respond to their particular maternal mental health needs. Maternity care providers should regard all recent immigrants as at high risk of PND and give closer observation and support as necessary.