The aim of the study is to identify the risk factors of protein energy malnutrition among children under five years of age in Assiut university children hospital. A correlation descriptive research design was chosen for this study. A convenient sampling design was followed to include children suffering from protein energy malnutrition aged below 5 years. Control group was purposively selected to be nearly age and sex matched. A total of 150 study and 150 control were included. The results revealed that PEM was more found in children in families of middle and low socioeconomic status with statistically significant differences, history of malnutrition in other sibling and younger age than others, statistically significant differences between practices of mothers in the cases than the control groups were found regarding breast feeding, artificial feeding and additional and adult food with low level of satisfactory practices observed among mothers in the cases than those in the control groups. From this study it can be concluded that several risk factors were found to be associated with PEM including, lower education level of the mother, number of children in the family as the number of children in the family decreased , the prevalence of PEM increased, low and middle family socioeconomic status, age of the child, children with the younger age are more vulnerable to have PEM than those of older age and mothers' practices regarding feeding of their children (breast feeding, artificial feeding as well as additional and adult food) unsatisfactory practices of mothers regarding feeding of their children increase the prevalence of PEM among their children. This study recommended that Supporting and promotion of breast feeding, avoid using of artificial feeding and bottles, health education to the mothers about proper feeding practices, breast feeding, artificial feeding and additional and adult food to prevent PEM, increasing mother's awareness related to risk factors of PEM and how to manage the different infections among their children and encourage vaccination at the appropriate time.