The susceptibility status of disease vectors, viz; Anopheles sundaicus and Aedes albopictus, against the insecticides used in public health need to be monitored at regular intervals, in order to target these vectors for effective control. In the island under study, viz, Car Nicobar, Anopheles sundaicus is the principal vector transmitting malaria parasite. Aedes aegypti and Ae. albopictus are reported to transmit dengue and chikungunya viruses. Since the latter mosquito species are highly prevalent in the area under study, susceptibility test for this species was determined. Susceptibility status of mosquitoes against DDT (4%), Malathion (5%), Fenitrothion (1%) and deltamethrin (0.05%) were investigated by the standard WHO susceptibility test kit. All the tested insecticides were susceptible to An. sundaicus, while for Ae. albopictus, DDT and fenitrothion were resistant. The resistance may be due to the extensive usage of these insecticides. Even though DDT is regularly used as indoor residual spray bi-annually for the control of malaria, An. sundaicus was found susceptible to DDT, may be partly due to their exophilic nature, which prevent them from contact to the sprayed surfaces. More thorough investigation need to be carried out to determine the bionomics of this mosquito, in view of the declining trend of malaria in this island.