The status of insecticides resistance was investigated in wild population of P. orientalisrnfrom Melka-Worer (Eastern Ethiopia) and Libo-Kemkem (Northern Ethiopia) andrnlaboratory breed P. bergeroti (F1) from collection in Melka-Worer between Decemberrn2007 and June 2008. Sand flies were exposed to six insecticides approved by WHO forrnindoor residual spray (IRS) and insecticides treated nets (ITNs). Standard WHOrndiagnostic bioassay kits for susceptibility studies with WHO discriminating doses ofrnDDT (4%), malathion (5%) and permethrin (0.75%), lambda-cyhalothrin (0.05%),rndeltamethrin (0.05%), alpha-cypermethrin (0.1%) impregnated papers were used. Knockrndown every 5 minute up to 20 minute and every 10 minute up to one hour and mortalityrnof sand flies 24 hour after one hour of exposure was recorded. In population of P.rnbergeroti from Melka-Worer mortality was over 98.8% with all insecticides tested (DDT,rnpermethrin, deltamethrin, lambda-cyhalothrin and malathion). The lowest 50% and 95%rnknock down time (KT50 and KT95) recorded were 18.2 (15.8-20.8) minutes and 31.1rn(27.3-37.9) minutes respectively for DDT followed by permethrin. However,rndeltamethrin revealed the weakest knock down effect with KT50 30.6 (27.6-33.9) minutesrnand KT95 46.3 (41.7-53.6) minutes. Phlebotomus orientalis in Melka-Worer showed morernthan 98.8% mortality to DDT, permethrin, lambda-cyhalothrin, alpha-cypermethrin, andrndeltamethrin. But it showed 93.75% mortality to malathion. The lowest KT50 was foundrnto be 8.2 (4.1-10.7) minutes for permethrin and the lowest KT95 21.3 (19.0-27.4) minutesrnfor lambda-cyhalothrin. DDT showed the lowest knock down effect at both values. ThernLibo-Kemkem population of P. orientalis showed over 98.8% mortality to all insecticides.rnBoth permethrin at KT50 and alpha-cypermethrin at KT95 showed highest knock downrneffect 11.7 and 21.1 minutes, respectively. But DDT showed the lowest knock downrneffect at both level. Based on WHO criteria where susceptibility is defined by mortalityrnrate greater than 98% 24 hour after exposure, no evidence for resistance were found. Thisrnimplies the use of these insecticides during epidemic or high prevalence of disease wouldrnbe effective to control sand flies in the study areas though the low level of resistance in P.rnorientalis to malathion in Melka-Worer needs to be confirmed.