Data from the Québec Longitudinal Study of Child Development were used to examine factors associated with postnatal depression and the links between self-rated health (SRH) and depressive symptoms in mothers 5 months after giving birth, according to immigration status. Postnatal depressive symptoms were measured using the 12-item Center for Epidemiologic Studies Depression Scale (CES-D). Immigrant mothers were classified according to their ethnocultural (majority or minority) group and compared with Canadian-born mothers. Logistic regression was used to evaluate the association between SRH and depressive symptoms. The prevalence of high depressive symptoms was larger among immigrants from minority groups (24.7%) than among immigrants from majority groups (8.3%) and Canadian-born mothers 11.2%). SRH was associated with depressive symptoms among Canadian- born mothers, but not among minority immigrant mothers. Canadian- born mothers integrated mental health into their assessment of overall health status, however, depressive symptoms among minority immigrant mothers were common, and their determinants warrant further research.