A number of acetals, aminoacetals, carboxamide acetals, and aromatic esters were synthesized and evaluated for topical repellency on human skin against Aedes aegypti mosquitoes. The aminoacetals exhibited the highest degrees of repellency, but none of the compounds rivaled N,N‐diethyl‐m‐toluamide in terms of duration of protection. Repellency was related to volatility, and it is concluded that useful repellency is associated with a volatility range corresponding to a boiling point of 100–150°/0.5 mm. Two benzylic ethers were also examined and one of these was comparable to N,N‐diethyl‐m‐toluamide in duration of topical repellency.