Under the experimental conditions of 26 +/- 10 degrees C, relative humidity 70-80%, 100 +/- 20 Lux and photoperiod 16 hours/day and using a membrane feeding method, the development of filarial larvae and the variations in reproductive capacity, gonotrophic cycle and longevity of An. sinensis infected with microfilariae of Brugia malayi were observed. The infection rate and infection intensity of filarial larvae in An. sinensis increased with the microfilarial density in the blood meal from 50 to 150 mf/20 microliters. The mature rate and IEI decreased when the density rose to 200 mg/20 microliters. The concentration ratio of mf in blood by An. sinensis was 1.2-1.4. In the 3rd gonotrophic cycle, the feeding ratio of infected mosquitoes became lower when the mf density rose to 150 mf/20 microliters, but the infection of filarial did not affect the number of oviposition, the regularity of egg-production activity and the hatching rate of eggs, while the quantity of egg-production increased when the mf density was 150 mf/20 microliters. The egg-production rate, and gonotrophic cycle were not basically influenced by filarial larvae infection. The multifeeding ratio was 16.7-48.4% in An. sinensis. The longevity of An. sinensis was extended by infection with mf density of 100 mf/20 microliters and shortened in infection with mf density of 200 mf/20 microliters. The authors conclude that "Brugia malayi-Anopheles sinensis" is a highly adapted "pathogen-vector" system.