Essential oils extracted by hydro-distillation from six plant species growing in Ethiopia,rnChenopodium ambrosioides (Chenopodiaceae), Laggera tomentasa (Asteraceae),rnEucalyptus camaldulensis (Myrtaceae), Cymbopogon citratus (Poaceae),Citrus sinensisrn(Rutaceae) and Ruta chalepensis (Rutaceae), were evaluated for repellency on forearmsrnof human volunteers against Anopheles arabiensis and Aedes aegypti under laboratoryrncondition (at 10% and 20% concentration). At 10% concentration oils of L. tomentosa, E.rncamaldulensis and Cy. citratus protected An. arabiensis for up two hours with meanrnprotection of 80.87% - 93.45%. Chenopodium ambrosioides produced 69.6% protectionrnat the first hour. Two other plants (R. chalepensis and Ci. sinensis) were only highlyrneffective for 1 hour. With increased concentrations (20%), L. tomentosa, E.rncamaldulensis and Cy. citratus gave the highest repellency (80.3% - 91%) and the longestrnduration of protection lasting for three hours against An. arabiensis. The repellency of Ci.rnsinensis and R. chalepensis only improved slightly from the 10% concentration.rnChenopodium ambrosioides did not provide significant protection even for one hour atrn20% concentration against An. arabiensis. At 10 % concentration, only one plant oil (Cy.rncitratus) gave about 91% protection lasting for one hour against Ae. aegypti. Thernremaining oils gave very weak protection starting even after the first hour of applicationrnagainst Ae. aegypti. At higher concentration (20%), five more plants except Ch.rnambrosioides continued to give high protection (81% - 93. 4%) for only one hour of postrnapplication against Ae. aegypti. It was also observed that Ae. aegypti was more tolerant tornall the candidate repellent plants than An. arabiensis at both concentrations. Thernexperiment also were evaluated the 1:1 combination of essential oils against An.rnarabiensis and Ae. aegypti. Almost all blends failed to produce significant protectionrnbeginning from the first hour. At 20% concentration there was only a slight improvementrnat the first hour of the experiments. As for An. arabiensis, the combination of oils did notrnimprove their potency as repellents against Ae. aegypti even at higher concentration ofrn20%. DEET, the standard commercial repellent gave much longer repellency (83- 100%)rnfor as long as six hours of the test period against An. arabiensis. DEET continued to givern> 90 % protection for about six hours against Ae. aegypti.