DDT and others organochlorine insecticides are very persistent substances. Clinical symptoms of intoxication have been reported in humans, although the main problem concerning such substances is bioaccumulation and biomagnification along throphic chains, leading to contamination of top predators and humans after them. In this review these characteristics are described, as well as some aspects of the control of vector borne diseases, like leishmaniasis and malaria, which were until recently, controlled by the health authorities using DDT.