An epidemiological study of bovine trypanosomosis was carried out from September 2007 to March 2008 in Goro and Ameya-Kota districts of Southwest Shoa Zone, Oromia National Regional State, Ethiopia. The objectives of the study were to determine the prevalence of the disease and associated risk factors, evaluate the apparent densities and distributions of tsetse and other biting flies and to know the community awareness concerning the disease and control method in the study area. The study methodology comprises seasonal cross-sectional studies in late rainy and dry seasons in 2007/2008 by using parasitological, entomological and questionnaire surveys. A total of 1200 animals, 600 in the late rainy and 600 in the dry seasons, were examined and the prevalence of trypanosomosis was found to be 33.5% and 17.83% in the late rainy and dry seasons, respectively, with a statistically significant difference (p