The main objectives of the study were: (1) to dete rmine the prevalence of bovine trypanosomernInfection in selected areas of the fltca project and (2) to assess the trypanocidal activit: ofrnDiminazene aceturate and isometamidium chloride and the impact of isometamidiumrnProphylaxis relative to no prophylaxis using cattle under natural challenge in the fieldrnThe study was conducted in seven areas (kone settlement, lako, shobe. Village i settlement,rnEgo kofele settlement sorelement and darimu). Which are located along three riverrnValleys in western ethiopia (upper didessa. Birbi r and sore-geba), the study was carried outrnFrom february to end of june 2001 and comprised of questionnaire survey. Cross sectionalrnStudy and isometamidium block treatment study.