Background: Globally, diarrheal diseases remain a leading cause of death. It is estimated for 1.87 million deaths each year, accounting for approximately 19% among children of under- five. Most of these deaths are due to dehydration and mismanagement or delayed management of the disease. Appropriate home treatment of under-five diarrheal diseases could prevent a significant number of child deaths and complications due to illnesses. Objectives: To asses prevalence of under-five diarrheal diseases, knowledge and practice of home treatment; it’s associated factors among mothers residing in selected sub-cities street of Addis Ababa town, Ethiopia, 2016. Methods: Cross-Sectional study was conducted among mothers residing in street who had under-five children in Addis Ababa, February 2016.A sample of 422 mothers were selected from four sub-cities by systematic sampling technique. Data was collected on 406 respondents through pre-tested structured questionnaire with face to face interview. Then, data were entered using EPI Info version 7 and exported to SPSS for analysis. Descriptive statistics and logistic regression analysis was conducted to assess knowledge, practice and their associated factors. Significances were considered at P -value less than 0.05 (P