BACKGROUND Postpartum depression (PPD) is a disorder that affects not only mothers, but also can lead to family, social, economic and vocational breakdown. The objective of this study was to determine the prevalence and factors associated with postpartum depression among mothers in an urban hospital setting in Malaysia. METHODS In this cross-sectional study, mothers attending routine visits at six to eight weeks postpartum at a postnatal clinic were assessed on socio-demographic data, obstetric history, social support, breastfeeding status and psychiatric history. Mini International Neuropsychiatric Interview (M.I.N.I.) was administered to establish a diagnosis of postpartum depression. RESULTS A total of 411 subjects participated in the study. The prevalence rate of postpartum depression was 6.8%. Univariate analysis found that being a housewife, having a cesarian section, low social support, family history of depression, previous history of depression and non-exclusive breastfeeding were significantly associated with postpartum depression. Predictors for postpartum depression were non-exclusive breastfeeding (P < 0.01, OR = 23.7, 95% CI 3.1-179.7) and previous history of depression (P < 0.05, OR = 82.3, 95% CI 1.2-5897.6). CONCLUSIONS The prevalence rate of postpartum depression in urban Malaysian mothers was comparable to the rates in other countries. Mothers who did no exclusively breast feeding their babies appeared to have more risk for postpartum depression. Therefore, screening for depression should become a routine during postpartum period and mothers must be encouraged to exclusively breastfeed their babies.