Diarrhea occurs world wide and causes 4% of all deaths. It is most commonly caused by gastrointestinal infections which kill around 2.2 million people globally each year, mostly children in developing countries. In 2008, Egypt prevalence of diarrhea in children aged under five years who receiving Oral Rehydration Solution is 28.4 %. Aim of the study was to assess mothers' knowledge and attitude regarding management of acute diarrhea .Subject and Method: cross sectional study was used. It included 600 randomly selected mothers from Assiut University Children's Hospital during 2012. Data Collection from mothers through two tools; first tool was interview questionnaire sheet. It consisted of two parts; first part included Socio-demographic data and the second part mothers' knowledge about diarrhea. The second tool included likert scale to assess mothers' attitude towards diarrhea. Results: The mean age of mothers was 26.08 ± 5.401, with no significant relation between mothers' age and their knowledge regarding diarrhea . As regards level of education, it was observed that about than two fifth (40.7%) of mothers were illiterate, while only 9.3% of them were high education. 57.8 % of mothers had satisfactory knowledge of about diarrhea. While, 86.2% of them had positive attitude towards diarrheal disease. Conclusion: There was a significant difference between mothers' knowledge and their education level. Also, there was a significant difference between numbers of diarrheal episodes and type of feeding. Recommendations: It is very important to provide good sanitation and improvement of housing conditions especially in rural areas.