Three synthetic pyrethroids and a new insect growth regulator (IGR) were evaluated in the laboratory against early 3rd instar Aedes aegypti (Linnaeus). Of all compounds tested the Atroban permethrin formulation was the most effective. Ae. aegypti were more susceptible at the LC90 level to the synthetic pyrethroids than to the IGR bay sir 8514 (2-Chloro-N-[[[4-(trifluoromethoxy) phenyl]amino]carbonyl]benzamide). LC90 values for Atroban, Ectiban, fenvalerate, and bay sir 8514 were 0.44, 3.84, 38.17 and 51.42 ppb, respectively.