Generally, Small ruminants are important source of the developing country as they provide more Abstract: A cross sectional study was conducted in sheep and goats that were kept under extensive management system in ZiwayDugda District, Eastern Arsi Zone, Oromia Regional State from November, 2016 G.C to April, 2017 G.C to determine prevalence and associated risk factors of GI nematodes. A total of 384 randomly sampled sheep and goats (281 sheep and 103 goats) were undergone coprological examination by simple floatation and McMaster egg counting technique. In the study areas, the overall prevalence of GIT nematodes in sheep and goats was 71.88% (276/384). Out of the total sampled animals, the prevalence of 75.8% (213/281) and 61.2% (63/103) were recorded in sheep and goats respectively. Based on coprological examination, in the study area, the prevalence of 54.17%, 8.33%, 3.13% and 6.25% accounted for Strongyle, Strongyloide, Trichuris and mixed type of infection between both species respectively. McMaster egg counting of positive samples revealed 42%, 33.7% and 24.3% as light, moderate and severe respectively. Species, age, sex and PAs of the animals were not shown statistically significant association (P>0.05) with prevalence of GIT nematodes. Body condition score of the animals has shown statistically significant difference (P<0.05). In general, high prevalence of nematode parasites was observed in the study area, which implies nematodes are the major constraints for production and productivity of these animals. Therefore, economically feasible, effective management and strategic de-worming of animals should be implemented for the prevention and control of the disease.