Background: Despite the demonstrated benefits of breast milk, the prevalence of breastfeeding, in-particular exclusive breastfeeding (EBF), in many developing countries including Ethiopia is lower than the international recommendation of EBF for the first six months of life Objective: To assess the practice of EBF and explore its determinants in Ethiopia and provide policy makers and NGOs with relevant information for future planning and interventions. Methods: Raw data collected from nine regions and two city administrations using stratified cluster sampling method by the Ethiopian Demographic Health Survey (EDHS) 2005 were used to study the practice and determinants of EBF countrywide. Analysis was based on children whose age was less than six months and alive at the time of interview that was extracted from the women’s database. Results: The overall rates of exclusive and full breastfeeding were 49.0% and 68.2% respectively. Maternal education, marital status, wealth index and age of the child were closely associated with EBF practices, nonetheless, in the hierarchical analysis; being not married, middle/ richer/ richest wealth index, and child age 0-1and 2-3 month were retained as the predictors of EBF (P<0.05). Conclusion: A range of maternal and child health attributes such as marital status, economical status and child age were found to influence the practice of EBF in Ethiopia. Actions to empower women and promotion of EBF campaign are recommended to achieve the fourth millennium development goal.