Introduction: under nutrition is a condition that results from eating a diet in which nutrients are not enough. It is the most common nutritional disorder in developing countries that contribute to morbidity and mortality among children.Globally 155 million under five children suffer from stunting. In Africa 59 million stunted and 14 million are wasted. Stunting attributable to one-third of children under 5 year and 14% of childhood deaths in developing countries.Under nutrition is also a major health problem in Ethiopia.This study assessedthe prevalence and associated factors of under nutrition in Dera woreda of South Gondar zone, Amhara regional state, Ethiopia. Objective:To assess the prevalence and its associated factors of under nutrition status among the age of 6-59 months in Dera Woreda of South Gondar, Amhara region state, Ethiopia 2017. Materials and Methods:community based cross-sectional study was conducted from May 15July, 2017 in Dera woreda. A systematic random sampling technique was used to select samples. A total of 840 under five children age of 6-59 months were selected for study.Both semi structured questionnaireand anthropometric measurement were done for data collection. Collected data was analyzedusing SPSS version 21. ENA for SMART 2011,software was used to compute weight for age z-score, height for age z-score and weight for height z-score. Descriptive statistics like frequency, percentages, crosstabulation and graph was used to describe the prevalence and bivariate and multivariable logistic regressions statistics were used to explore associated factors of under nutrition. Results: The overall prevalence of under nutrition among children whose age 6-59 months in the study area showed that 228(27.1%), 317(37.7%) and 74 (8.8%) of children were underweight, stunted, and wasted respectively. Family monthly income less than 750 ETB (AOR=1.7:95% CI=1.2, 2.6) and between 750-1000 ETB (AOR=1.85:95% CI=1.32, 2.604) and children received pre-lacteal feeding were associated with stunted (AOR=2.4:95% CI=1.78, 3.24). Family monthly income less than 750 ETB (AOR=1.59 95% CI: 1.06, 2.40), child did not feeding of colostrum (AOR=1.46:95% CI=1.06, 2.01) and diarrheal disease in the past two weeks (AOR= 3.12, 95% CI: 2.20, 4.41) were associated with underweight. Use of untreated water (AOR= 0.329, 95% CI: 0.19, 0.56) and unavailability latrine were (AOR= 1.942, 95% CI: 1.19, 3.11) were associated with wasted. Conclusions: There is high prevalence rate of stunting, wasting and underweight among children with age group of 6-59 months in Dera woreda. Monthly income, pre lacteal feeding, child had not feeding of colostrum, diarrheal disease, unavailability of latrine, house hold that used untreated water for drinking were factors for under nutrition.