Diarrhea is the second leading cause of death in children under five years old, and is responsible for killing around 760, 000 children every year, special in developing counters due to lack of Knowledge and practice in Diarrheal disease management. The main aim of this study was to assess mothers' knowledge and practice among mothers who have under five children, in two blocks of Rayagada, Odisha, India. A community based crosssectional study deign was conducted. The study was done from April-May 2014. To determine the sample size a single proportional formula was used. According to this formula the sample size of the study was 846. Multi-stage sampling technique was employed to select the study areas and study units. Among five kebeles, two kebeles were selected by simple random sampling techniques. Standardized interview questionnaires were adapted and modified from related articles and journals to collect data on the socio-demographic variables and factors associated with it. Pre-test was done in none sampling kebeles. Data were entered in Epi-info (version 3.5.1) statistical software package then exported to SPSS software package version 16.0 for further analysis. A total of 846 participants were included in the study. Of these, the response rate was 830(98.1%). Five hundred twenty-eight 528(63.6%) of them had good knowledge and 381(45.9%) of them had good practice. The finding of this research indicated that 63.6% of mothers had good knowledge towards Diarrhea management while 54.1% of mothers had poor practice on Diarrhea management.