Abstract: In Fujian, there are two species of human filariae, Wuchereria bancrofti and Brugia malayi, transmitted by Culex fatigans and Anopheles lesteri anthropophagus respectively and the microfilariae of both worms show well marked nocturnal periodicity. Remarkably different geographic distribution between the two worms is due to the different breeding behaviour of their vectors. The infection rate of B. malayi is often higher than that of W. bancrofti, and the infection rate of both parasites is higher in male. However, the microfilaria rate of B. malayi is not parallel with age, because the worm is liable to induce immunity. A good result could be obtained by raising the standard of living and control of breeding of the vector. Prevalence of the disease can be monitored by mosquito .survey. Though the source of infection of human filariasis in animal is not found, a lot of filaria species in animals especially in birds are present. It is necessary to further investigate so as to differentiate the species parasitizing animals from man.