Abstract: Under-nutrition during infancy and early childhood, when the developmental process are in very dynamic state, substantially increase vulnerability to different types of adverse health effects including infection, immune deficiency and other disease, leads to increased risk of premature death. In 2012, globally 162 million children were stunted, 99 million children were under weight, 51 million were wasted and 45% of 6.9 million child deaths occurred in 2011, which were related to under-nutrition. Methodology: Major determinants of malnutrition in sick children fewer than five years of age were evaluated and compared with age matched well nourished children. The nutritional statuses of the subjects (80 malnourished and 80 well nourished) were determined by measuring MUAC. Different socio-economic indicators of the subjects were evaluated and correlated with malnutrition and disease severity to find out the determinants of malnutrition in children of Jimma town. Results: Most of the severely malnourished were resident of rural area (88.8%). Out of 80 malnourished children, 51(63.75%) were belong to families having monthly income <500 birr, where as in well nourished group (80 children) only 22 (27.5%) were belong to families having monthly income <500 birr. In malnourished group 61.8% of children were having diarrheal episode during past 2 weeks. The prevalence of diarrhea in malnourished group was 21.3% which is higher than well-nourished group. Conclusion: Place of residence, literacy status of mother, family size, family income, vaccination, presence TB, marital status of mother, diarrhea, timing of supplementary diet and water sources are the major determinants of SAM
