Resistance to cypermethrins was recorded in Bemisia tabaci populations of Pakistan using a leaf-dip method. A very high resistance to cypermethrin was found in most of the populations during 1993 to 1995. Then, due to reduced use of cypermethrin targeted against whitefly, and owing to the introduction of new chemistries with novel modes of action and having no cross resistance to conventional insecticide groups, cypermethrin resistance generally dropped to very low levels during 1996 to 1999. Resistance to zetacypermethrin was mostly low and to alphacypermethrin was still very low. Some of the whitefly populations, which had a low resistance to alpha- and zeta-cypermethrin, showed a moderate resistance to cypermethrin. This implies that different mechanisms of resistance differ in conferring resistance to different isomers of cypermethrin in whitefly. The use of novel chemistries in rotation along with other IPM tactics is recommended to manage whitefly and its resistance development in future.