Six controlled-release personal-use topical insect/arthropod repellent formulations of diethylmethylbenzamide (deet) were evaluated in an environmental chamber on volunteers for repellency against the mosquitoes Aedes aegypti and Ae. taeniorhynchus under three climatic regimens: basic variable high humidity (tropical environment), basic constant high humidity (forested and wet environment) and basic hot (hot-dry environment). The best protection under all the climatic regimens was provided by the Biotek formulation. In a tropical environment, some formulations induced more biting from mosquitoes than the concurrent untreated control in the late hours of the testing. Repellency was not directly related to the deet concentration in the various controlled-release repellent formulations.