An investigation into the susceptibility of malaria vectors, Anopheles gambiae Giles and An. funestus to DDT, permethrin, deltamethrin, propoxur, lambda-cyhalothrin, bendiocarb, fenitrothion, cyfluthrin, malathion and resmethrin insecticides was conducted in the Kassena-Nankana District of Northern Ghana. The objective of this study was to determine the susceptibility status of malaria vectors to insecticides. Field populations of mosquitoes from irrigated and non-irrigated areas were tested using World Health Organization (WHO) and CDC bioassays. The susceptible laboratory reference strain (Kisumu) was used as control for the CDC bottle assay. Both the WHO and CDC assays indicated a relatively high level of deltamethrin, permethrin and DDT resistance in the populations of mosquitoes tested from each areas. Resistance to deltamethrin ranged from 6-43%, followed by DDT (11.3-29.2%) and Permethrin (5.7-22.5%). Lower resistance levels were detected for lambda-cyhalothrin (1.2-13.2%) and malathion (2.5-7.1%), and the remaining insecticides produced 100% mortality in our assays. Anopheles funestus showed a significantly higher resistance to malathion than did An. gambiae. Both assays indicated a greater than two-fold increase in resistance lelvel in the non-irrigated versus irrigated area. The implications of these findings and their impact on the use of insecticide-treated nets in this area are discussed.