The laboratory rabbit was evaluated as a model for screening topical mosquito repellents, using data obtained in tests of deet (N,N-diethyl-3-methylbenzamide) against Aedes aegypti on humans and rabbits. Host-specific differences in the action of the test material were quantified by multiple regression analysis. The test material was less effective but more persistent in tests on rabbits, and responses of the mosquito test population were more variable.