Background: To determine and analyse the risk factors leading to severe acute malnutrition (SAM) in children under 5 years of age attending nutritional rehabilitation centre of our hospital.Methods: This questionnaire based case control study was conducted from January 2016 to December 2016 on SAM children. For comparison children attending outpatient department without any evidence of malnutrition were included. These SAM children were admitted to the nutritional rehabilitation centre of Cheluvamba Hospital attached to Mysore Medical College and Research Institute, Mysore, Karnataka.Results: A total of 103 SAM cases were compared with 100 controls. The sociodemographic risk factors were age less than 2 yrs, more family members (55.3% had 5 to 8 members), Birth spacing less than 2 years (39.8%), open air defecation (37.9%) and living in kucha house (32%). The dietary risk factors which were statistically significant were poor appetite (33%), prelacteal feed (19.4%), lack of exclusive breast feeding (42.7%), discontinuing breast feed before 2 years (74.8%), receiving complementary feed before 6 months (67%), bottle feeding (32%), calorie deficit (79.6%), protein deficit (66%) and feeding difficulty (17.5%).Conclusions: The social risk factors identified in this study were large family size, low income, more number of siblings and living standards like type of house, open air defecation. The nutritional risk factors were giving prelacteal feed, not giving exclusive breast feeding until 6 months, starting complementary feed before 6 months and giving food low in calories and protein.