A trial aimed to evaluate the efficacy of Deltamcthrin (0.4% impregnated odour-baitedrntargets and I % pour-on formulation app lied to animals) in reducing the incidence of bovinerntrypanosornosis and comparing the corresponding cost-effectiveness of both strategies wasrnconducted in two selected IOXIOkm Universal Transverse Mercator Grids of the SouthernrnTsetse Eradication Project (STEP) area in the Southern Rifl Valley of Ethiopia. The Gridsrnselected were I-B & G5 designated as study Sites I & Il respectively. The tTial was underwayrnfrom late September, 2003 to early April, 2004. The accomplishment of the trial includedrnbaseline survey (Questionnaire, Parasitology, and entomology), intervention with insecticidern(Dcltamethrin 0.4%) impregnated odour-baited targets at Site I(Grid H3) and DeltamethrinrnI % 'pour-on' application to cattle at Site II (Grid G5) and monthly monitoring of thernincidence 0 f disease a nd apparent density of tsetse fly. Following the deployment 0 f 460rntargets (0.4% Deltamethrin impregnated and odour-baited) at a density of 4 targets fkm2 atrnthe trial Site I, the relative abundance of tsetse fly (G. pal/idipes) population declined from arnpre-intervention catch of 1.35 flies/trap/day to 0.05 flie s/trap/day during t he final trappingrntime in April, 2004 with about 88.88% overall reduction achieved. The associated diseasern(uypanosomosis) status was monitored by monthly blood sampling from the sentinel animalsrnestablished prior to the intervention and the incidence in cattle dropped from 10.75% (firstrnmonitoring) to 1.8% (last monitoring) with about 83.25%. The prevalence of the disease hadrnalso dropped to 9% (P< 0.01) as compared to the pre-intervention result of 23% and as arnresult, an overall reduction of 60% was achieved. The corresponding overall mean pevrn(packed cell volume) record had sho'T1 an improvement from 21.8% of the pre-interventionrnto 25.5 % (P