Background: Exclusive Breast Feeding (EBF) is defined by WHO as giving the infant no other food or drink, not even water, apart from breast milk, expressed with exception of drops or syrups consisting of vitamins, mineral supplements or prescribed medicine. The feeding options for women who are HIV negative is to exclusively breastfeed (EBF) their newborn for the first six months, then complementary foods after six months and continue breastfeeding (BF) for two years and beyond. Objective: To assess exclusive breastfeed practice and its determinants among HIV positive mothers attending government and private selected health facility in Arada subcity, Addis Ababa, Ethiopia. Method: Institution based cross sectional study was conducted among HIV positive mothers whose infants‟ age were less than twelve months attending PMTCT clinics in Arada sub- city selected health institutions. A structured pre-tested questionnaire using interview technique was used for data collection and 232 HIV + mothers were included in the study. The data was entered and analyzed using SPSS version 20. Ethical clearance was obtained from BDU ethical review committee and AARHBERC. Result: Exclusive breast feeding (EBF), Replacement breast feeding (RBF) and mixed breast feeding (MBF) were 78.02%, 11.21%, and 10.78% respectively. ANC follow up, employment status and residence had association with Exclusive breast feeding practice (p<0.05). But the result in multiple logistic regression showed that only deliver attendant had the most significant positive relationship with practice of HIV positive mothers on EBF (p<0.05). Conclusion: The study identified gaps in EBF practice which seem to affect appropriate infant feeding. Mixed feeding, and undesirable practice in infant feeding was reported in this study. Birth attendances with nurse were 3.87 times more likely to EBF their child than with doctor.