The relative toxicities of 8 repellents (DMP, Rutgers 612, DEET, IR3535, Picardin, PMD, AI3-35765, and AI3-37220) were evaluated by topical application against females of Aedes aegypti, Culex quinquefasciatus, Anopheles quadrimaculatus, and An. albimanus. Based on 24-h LD₅₀ values, the most toxic repellent against all 4 mosquito species was AI3-37220, with values of 0.25, 0.20, 0.16, and 0.11 µg/mg for the listed 4 mosquito species, respectively. The least toxic of the 8 repellents tested was DMP, with LD₅₀ values of 5.40, 4.72, 2.50, and 1.83 µg/mg, respectively. Based on the 24-h LD₅₀ values, An. albimanus was the most susceptible species. The findings of the study reported herein provide a comprehensive examination of the toxicities of 4 currently used, 2 formerly used, and 2 experimental repellents against 4 mosquito species.