Diarrhoea disease is a common childhood death in the developing countries. WHO (2013) estimates that diarrhoea kills 2,195 children every day. Diarrhoea disease account for one in nine child death worldwide, diarrhoea is the second leading cause of death among children under the age of 5. About 88% of diarrhoea associated deaths are attributed by unsafe water, in adequate sanitation and insufficient hygiene. Objective: To assess the knowledge regarding management of diarrhea among mothers of under-five children and to associate the knowledge of mothers about management of diarrhea with selected socio demographic variables. Methods: A descriptive study was conducted in Saveetha medical college and hospital. 50 samples were selected by convenient sampling technique. Data gathering was carried out with structured questionnaires sampling technique among the study was conducted among the mother of school age children at SMCH. Result: Among 60 samples, Out of 60 mothers 55 (91.6%) of them had inadequate knowledge and 4(6.6%) of them had moderately adequate 1(1.6%) had adequate knowledge regarding management of diarrhea.