Brugia malayi and B. Pahangi microfilariae from gerbil intraperitoneal infections were inoculated into the thorax of male and female Toxorhynchites amboinensis and developed into third-stage larvae as early as 11 days. In a comparative study with Aedes togoi fed on microfilaremic gerbils, third-stage larvae were found at 10 days. Some third-stage larvae of B. malayi inoculated into gerbils developed to advanced stages. Third-stage larvae of Wuchereria bancrofti were recovered in low numbers from Tx. amboinensis and Tx. aurifiuus inoculated with microfilariae recovered from human blood by membrane filtration. Development of all filarial species was similar in both male and female mosquitoes. Toxorhynchites species are plant feeders and therefore reduce the hazards of laboratory transmission of pathogenic agents. Because of their large size, manipulations with this mosquito species are easy and the size allows for a larger inoculum to be used. This group of mosquitoes should develop into useful laboratory vectors for the transmission of arthropod-borne diseases.