Introduction. Physiological resistance of natural population of Aedes aegypti to insecticides contributeto the decreased efficacy of chemical control as a main control strategy during dengue outbreaks.Objective. The susceptibility status of Ae. aegypti was assessed for the carbamate propoxur, theadulticide malathion and the larvicide temephos on 13 natural populations of Ae. aegypti immatureforms were taken from 8 Colombian localities. These included the following: Bucaramanga (1), Sabanade Torres (2), Girardot (2), La Mesa (2), Villavicencio (2), Puerto López (2), San José del Guaviare (1)and Florencia (1).Materials and methods. Susceptibility tests mainly consisted of the standardized bioassay outlinedby WHO (1981) and CDC bottles (1998). Colorimetric tests were undertaken to determine enzymelevels possibly responsible for the reduction of susceptibility to organophosphate and carbamateinsecticides.Results. All specimens demonstrated susceptibility to malathion and propoxur insecticides. Four of the13 populations revealed susceptibility to the temephos larvicide. Seven of 11 populations showed alimited increase in values for nonspecific esterase enzymes. The Bucaramanga population was the onlyone which showed an increase in the cytochrome P450 monooxygenases enzymes. Neither populationwas found with modified acetilcolinesterase.Conclusions. The widespread susceptibility to organophosphates used as adulticides indicated thatmalathion, the most used insecticide in Colombia, remains effective in interrupting the transmission of dengue. Physiological resistance to insecticides occurring in communities of a single township provedto be a localized phenomenon.doi: http://dx.doi.org/10.7705/biomedica.v32i3.680