Tsetse transmitted animal trypanosomosis is a serious constraint in animal production andrnAgricuhural development in Ethiopia. The vast area adjacent to the Ghibe valley in SouthrnWest Ethiopia is tsetse infested where animal trypanosomosis is a serious threat to livestockrneconomic development. The objectives of the study were to investigate the prevalence andrnmagnitude of bovine trypanosomosis in representative and selected villages of Sokorurnworeda. to asses and analyze the efficacyrn trypanocidals in use. to determine the extent ofrn the disease based on the study findings to point out and search for the possible. Sustainablern and effective control options of tsetse transmitted trypanosomosis. The study was rnconductedrn from September 2005 torn Februar 2006. The stud methodology was based on questionnairern survey , seasonal cross sectional studies and longitudinal study forrn trypanocidals drug efficacyrn in villages of Abelty and Tiroshashama. The result of the questionnaire suney revealed thatrnall the interviewees agreed that trypanosomosis was the most important and majorrnproblematic disease in their area. Cross sectional study was done on 515 sampled - cattle.rnAnimals were examined using parasitological method a buffy coat technique (BCT). A totalrnof 64 monoconical traps werern deployedrn along suspected tsetse habitat in the range of 1.392-rn1,629 meters above sea level. And entomologicalrn survey revealed that Glossina m.rn submorsitans was the highly prevalent tsetse fly species followed by Glossina pallidipes andrnwith several Stomoxys spp. The apparent density tsetse was relatively higher in late rainyrnseason (0.194 flies /traprn/day) at Abelt in late rainy season and none in dry seasonrn respectively where as in Tiroshashama village thern fly catch was 0.028 fly/trap/ day in laterainy and 0.017 fly /trap/ day of G.m. submorsitans and 0.017 G.pallidipes was caught in dry season. Thernflrny catch was declined may be because of the high temperature of the dry season low humidity and bush fire which occurred few weeks before the study period and such condition may damage the suirrable tsetse habitat and also inavailability of favorablern hosts in the area. forced the flies to evacuate to the extreme low land areas towards the riverrn basins.rnNeverthelessrn high catches of Stomoxys 10 flies /traprn/ day in late rainy season atrn Abelty and none flies of Stomoxys/trap/day in dryseason at Abelty. rnThirteen flies ofrn stomoxy /trap/ day in dry season 20 flies ofrn Stomoxys /trap/day in dry season atTiroshashama village were caught. In the parasitological sunvey a total of 515 animals out ofrnwhich 180 cattle in late rainy season 335 cattle in dry season were examined with buffy coatrntechnique and the result showed the prevalence of trypanosomosis was highest in dry seasonrnrainy season was observed. A significa nt difference ( P < 0.05) was noticed between the meanrn PCVvalues in parasitacmic (95 % C I 21.24,23.59) aparasitaemic (95% Cl 23 .93,24.73)rn cattle.