Cx. tritaeniorhynchus, Cx. vishnui, two important vectors of Japanese encephalitis, were collected from Ha Giang and Phu Tho provinces in September and November, 2011. The patterns of insecticide susceptibility to alphacypermethrinm, deltamethrin, lambdacyhalothrin, permethrin, malathion and were determined. The results showed that:Cx. tritaeniorhynchus was found resistant to alphacypermethrin, deltamethrin, lambdacyhalothrin, permethrin (mortality, 11-48 percent). Cx. vishnui, was found tolerant to alphacypermethrin, deltamethrin, lambdacyhalothrin, permethrin and malathion (mortality, 83-97 percent), but resistant to alphacypermethrin in Thanh Van, H. Quan Ba (Ha Giang) (mortality, 51 percent), resistant to lamdacyhalothrin, permethrin (mortality 14 percent, 38 percent, Respectively). It was resistant to alphacypermethrin, deltamethrin, lambdacyhalothrin, permethrin (mortality, 37-51 percent), and tolerant to malathion (mortality, 93 percent).