Dissertation (MSc Midwifery)There is no other better way proven to safeguard an infant's health in the first six months of life than exclusive breastfeeding. Mothers breast milk is valuable in all aspects of an infants physical and mental growth as well as immune development. This study assessed factors influencing exclusive breastfeeding among lactating mothers infected with HIV and its associated health outcomes of infants. A hospital-based analytical cross-sectional study was conducted in the southern highlands region of Tanzania. A random sampling procedure was employed to obtain 372 HIV-infected mothers of infants of six to twelve months who were still breastfeeding at the time of data collection. An interviewer-administered structured questionnaire was used to capture data from the study participants. Bivariate and multivariate logistic regression was used to assess predictors of EBF among HIV-infected lactating mothers. Statistical package for social science (SPSS v.20) software was used for data entry and analysis. This study included 372 women who had been diagnosed with HIV infection before or during pregnancy. Their mean age was 30.66 ± 5.72 (range 18-49 years), the mean age of their children was 9.74 ± 2.08 (range 6-12 months). The study found that about 58.1% of mothers infected with HIV practiced exclusive breastfeeding for the first six months. 199 (53.5%) had adequate knowledge of exclusive breastfeeding and 194(52.2%) expressed positive perception towards the practice of exclusive breastfeeding. The most perceived barrier to exclusive breastfeeding was insufficient breast milk 240(64.5%), 24(6.5%) of the exposed infants were HIV positive by dry blood slide and 84 (22.2%) were found to be malnourished. Predictors for EBF were adequate knowledge (AOR=5.114, 95%Cl: 3.200-8.172, P=<0.001), positive perception of EBF (AOR=3.506, 95%Cl: 2.248-5.468, p=<0.001), adequate ANC visits (AOR=1.756, 95%Cl: 1.094-2.817, P=0.002), and those who did not experience breast problem (AOR=3.908, 95%Cl: 1.891-8.075, p=<0.001 Prevalence of exclusive breastfeeding was found to be high. About half of HIV lactating mothers had adequate knowledge of EBF and expressed positive perception toward exclusive breastfeeding. Adequate knowledge, positive perception toward EBF, adequate ANC visit, and having never experienced breast problem was the predicators for EBF practice. Strengthening adherence to ANC routine visits, counseling on breastfeeding and improving mothers knowledge of exclusive breastfeeding would contribute to the enhancement of EBF practice in this region.