Experimental infections of Onchocerca gutturosa, O. cervicalis, and O. volvulus were induced in males and females of a strain of Aedes aegypti originally selected for susceptibility to Brugia malayi. Mosquitoes were inoculated intrathoracically with microfilariae from the skins of animals infected with the three parasites. Percentages of female Ae. aegypti harboring third-stage larvae 9 or more days after inoculation were 22.5% for O. gutturosa, 11.1% for O. cervicalis and 14.4% for O. volvulus. Infection rates among male mosquitoes were 39.5% for O. gutturosa and 16.15% for O. cervicalis. Although O. volvulus did develop to the third larval stage in males, high mosquito mortality prevented estimation of the rate of susceptibility. Infection rates among mosquitoes inoculated with cryopreserved microfilariae of O. gutturosa were similar to those in mosquitoes inoculated with microfilariae from fresh skin snips. Of the three species of filariae studied, only O. volvulus had a pronounced pathological effect on the inoculated mosquitoes. While most larvae recovered from Ae. aegypti were normal, pathologies similar to those exhibited by other filariae developing in abnormal hosts were noted in some individuals.