Background and Objective: HIV infection is also a cause of postpartum depression, however, in Vietnam, there has not yet the prevalence of postpartum depression in HIV infected women. The objective is to determine prevalence and related factors of postpartum depression in HIV infected women. Materials and Methods: From November 30th, 2012 to March 30th, 2014, a prospective cohort study is done at Dong Nai and Binh Duong province. The sample includes135 HIV infected women and 405 non infected women (ratio 1/3) who accepted to participate to the research. We used “Edinburgh Postnatal Depression Scale (EPDS) as a screening test when women hospitalized for delivery and 1 week, 6weeks postpartum. Mother who score EPDS ≥ 13 are likely to be suffering from depression. We exclude women who have EPDS ≥ 13 since just hospitalize. Data are collected by a structural questionaire. Results: At 6 weeks postpartum, prevalence of depression in HIV infected women is 61%, in the HIV non infected women is 8.7% (p < 0.001). There are statistical significant differences (p<0.05) between two groups for some factors: education, profession, income, past history of depression, child’s health, breast feeding. Logistical regression analysis determine these factors are related with depression: late diagnosis of HIV infection, child infected of HIV, feeling guilty of HIV infected and feeling guilty with their family. Multivariate regression analysis showed 4 factors are related with depression: HIV infection, living in the province, child’s health, past history of depression. Conclusion: Prevalence of postpartum depression in HIV infected women is 61.2%; risk of depression of postnatal HIV infected women is 6.4 times the risk of postnatal HIV non infected women, RR=6.4 (95% CI:4.3 – 9.4). Domestic women have lower risk than immigrant women from other province, RR=0.72 (95% CI:0.5 – 0.9). Past history of depression is a risk factor with RR=1.7 (95% CI:1.02 – 0.9. Women whose child is weak or die, RR=1.7(95% CI:0.9 – 3.1). Keywords: Postpartum depression, HIV-positive postpartum women