INTRODUCTION: Children under five years constitute the one of the most vulnerable group of a country. Their nutritional status and mortality rate is a sensitive indicator of community health services and nutritional status of that community. In developing countries, the nutritional status of children depends on socioeconomic status, immunization status, breastfeeding practices awareness of diseases such as diarrhea and acute respiratory tract infection, educational status of mother and availability of safe drinking water etc. OBJECTIVES: To study the prevalence of malnutrition among the under -5 children in an urban slum area under urban field practice area of tertiary care hospital &to study the various risk factors affecting malnutrition among them. MATERIAL & METHODS: A Community based descriptive Cross-Sectional Study was conducted on 175 Children under 5 years of age in a slum area under Urban field practice area of a tertiary care hospital during 1st November 2021 to 31st December 2021. Anthropometric measurements were taken using shakir’s tapes and calibrated weighing machine. RESULTS: Present study shows that the overall prevalence of malnutrition is 63.99% in under-5 children out of which 26.28% study subject was moderately malnourished and majority i.e. 37.71% study subjects was severely malnourished. Out of various risk factors studied, age and socioeconomic status was found significant with p value of 0.04 and 0.003 respectively. CONCLUSION: Nearly one third of children were underweight (32%), half of the children were stunted (51.42%) & one fifth of children were wasted (16.57%). Thus chronic malnutrition was more prevalent in the urban slum area.