Under-five mortality is defined as the likelihood for a child born alive to die between birth and fifth birth day. Mortality of under the age of five has been the main target of public health policies and is a common indicator of mortality levels, especially in developing countries. It is also viewed as an indicator of the level of development, health and socioeconomic status of the population. The objective of this study was to identify determinants of under-five mortality in Ethiopia using the 2011 EDHS data. To achieve the objective of this study descriptive statistics and count regression models were used for data analysis using socio-economic, demographic and environmental related variables as explanatory variables and the number of under-five deaths per mother as the response variables. According to Ethiopian Demography health Survey, 2011 report the level of under-five mortality in rural parts of Ethiopia is 114 deaths per 1000 live births. Factors influencing the number of under-five deaths have been identified. The study revealed that mother’s age at the first birth, breastfeeding status, wealth index, current mother working, region and mother’s level of education had statistically significant on the number of under-five deaths in rural parts of Ethiopia.