Insecticide susceptibility tests were conducted on the adults of four anopheline species namely. Anopheles annularis, An. culicifacies, An. stephensi and An. subpictus against the diagnostic doses of six insecticides, viz. DDT (4.0%), dieldrin (0.4%), malathion (5.0%). fenitrothion (1.0%), propoxur (0.1%) and permethrin (0.25%) in District Bikaner (Rajasthan). A time dependent effect has been observed with each insecticide. All the four species were found resistant to DDT and dieldrin and susceptible to fenitrothion and permethrin. An culicifacies and An. subpictus showed susceptibility to malathion, while further verification for the other two species was required. However, with propoxur An. annularis showed resistance, whereas for other three species further studies are required. DDT and dieldrin, the two organochlorines, were found least effective as compared to organophosphates and carbamates.