Background: Globally, diarrhoea disease is a major cause of morbidity among children under 5 years (under-fives). In Africa, there are 696 million cases of diarrhoea among under-fives every year. Diarrhoea accounted for about 4.7% of outpatient visits among under-fives in Kenya, a common observation in many developing countries. It appears that even with the well drummed up public health and maternal health programs among the developing countries, diarrheal infections continue to be a major challenge in the lives of children under five years. The object of this study was to examine the behavioral determinants of diarrhoea morbidity among children under 5 years. This was driven by observation of the challenges posed by diarrheal infections in the lives of young children in Migori county in Kenya. Study design involved a descriptive study where a questionnaire was used as the research instrument for data collection. A sample of 216 respondents was studied. Results: According to results, the behavioral factors associated with under five diarrhoea included hand washing with soap (p<0.001; food storage method (p<0.001); and heating stored food before feeding (p<0.001). Hand washing is important because it prevents transmission of infectious agents of diarrhoea after being in contact with excreta such as after changing babies’ nappies. In addition, leftover food can act as a breeding ground for bacteria since the food has been in contact with saliva and skin. There is a need for interventions that promote appropriate practices in food storage method and emphasize heating storage foods. In conclusion, the study emphasizes that hygiene practices should be encouraged, and intervention programmes should be implemented to create awareness on proper refuse and wastewater disposal.