Normal and branched chain aliphatic monoethers of triethylene glycol are effective topical mosquito repellents. In terms of duration of protection, they are generally superior to the corresponding diethylene glycol analogs, and some are superior to diethyltoluamide. The n heptyl monoether of triethylene glycol affords double the protection time of diethyltoluamide under controlled laboratory conditions, and appears to be a useful new mosquito repellent.