The susceptibility of Aedes aegypti Linnaeus 1762, Culex quinquefasciatus Say 1823 and Anopheles gambiae Giles 1902 was tested on 0.75 % permethrin pyrethroid in the laboratory. All Larval and pupal stages of the mosquitoes were collected from different localities within Zaria, Nigeria and reared to adulthood in the laboratory. The adults that emerged were tested on 0.75 % permethrin strips using WHO Standard Test Kit. Mortalities were recorded at five minutes interval for 1 hr and maintained

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... r 24hrs post-exposure on 7 % sucrose solution after which a final mortality was recorded. The Knockdown times (KDT50 and KDT95) were determined by Probit Analysis. 100 % mortality was obtained for Ae. aegypti and Cx. quinquefasciatus after 1hr and 24hr exposures, respectively, whereas An. gambiae recorded 92.11 % and 90.91 % mortalities after 1hr and 24hr exposure, respectively. The KDT50 and KDT95 did not differ significantly (P>0.05) between Ae. aegypti and Cx. quinquefasciatus but differed significantly (P<0.05) with An. gambiae. The study shows that Ae. aegypti and C. quinquefasciatus are susceptible to permethrin whereas An. gambiae is resistant to the insecticide in the area.