Medical entomology deals with major vectors responsible in the transmission of diseases. Mosquitoes, flies, flea, lice, ticks, mites and Cyclops are discussed under morphology, life cycle, disease transmitted and control. Major insecticides like DDT, BHC, Pyrethrum and Paris green are detailed. Rodents and public health is highlighted. Diseases under zoo-noses are enumerated. Chapter is concluded with integrated vector control and integrated approaches to the environmental problems.