A survey was conducted in Hawagelan district, West Wellega zone, western Ethiopia from November 2009 to March 2010 to determine the prevalence of bovine trypanosomosis and the prevailing species of trypanosomes as well as to assess host related risk factors. Blood samples collected from 384 randomly selected cattle were subjected to parasitological and haematological analysis. The overall prevalence was found to be 8.6%. Trypanosoma congolense was the predominant species in the area (72.7%). The prevalence among the species of trypanosomes showed statistically significant difference (P<0.05). However, it was not statistically significant between sex and the different age groups (P> 0.05). The mean packed cell volume (PCV) value of the infected animals was lower (20.8%±3.2) compared to non-infected animals (24.9%±3.8). There was statistically significant difference (P<0.05) in the PCV values of infected and non-infected animals. Moreover, animals with different body condition exhibited statistically significant variation (P<0.05) in the prevalence of trypanosomosis. Finally, this work showed that trypanosomosis is an important disease affecting the health and productivity of cattle in the district. Hence, due attention should be given to this sector so as to improve livestock production and agricultural development in the area.