BACKGROUND:Malnutrition has been responsible, directly or indirectly for 60% of the 10.9 million deaths occurring annually among children under five years of age. Over two thirds of these deaths are often associated with inappropriate feeding practices occur during the first year of life.Breastfeeding is an unequalled way of providing ideal food for the healthy growth and development of infants. Exclusive breastfeeding is the most effective intervention and a good knowledge and attitude is necessary among mothers to practice appropriate breastfeeding to reduce infant and under five morbidity and mortality.rnOBJECTIVES: The aim of this study was to assess knowledge, attitude and practice of exclusive breastfeeding among mothers and to identify determinants of breastfeeding practice in selected public health institutions of Arada Sub- City, Addis Ababa, Ethiopia.rnMETHODS:A cross-sectional facility based study was conducted among 383 mothers who have infants below six months old in three selected health facilities one Hospital and two health centers of Addis Ababa in March to April 2015. Random sampling with proportional to size allocation technique was applied. Structured questionnaire was used to interview the selected mothers, experienced interviewers and supervisor were collected the data using a pretested questionnaire. Data was analyzed using SPSS windows version 20.0 software.rnRESULTS: A total of 383 mothers who had children aged less than 6 months were interviewed. The ever breastfeeding rate in this study was found to be 99.7% and timely initiation of breastfeeding and EBF rate based on 24 hours recall were 65.8% and 74.3% respectively. The study findings revealed that there is a good practice of exclusive breastfeeding. Knowledge of additional food to be given with breast milk from birth to 6 months(P