Amounts of Certain elements in Anopheles sinensis, both normal ones (emerged mosquitoes, d0, d5, d8, d12 and d18 after taking blood meal) and those infected with Brugia malayi microfilaria (d5, d8, d12 and d18 after infection), were determined using IL-551 and PE-603 atomic absorption spectrometer (AAS). The results showed that 9 kinds of trace elements including Fe, Zn, Cu, Cd, Al, Pb, Mn, Ni and Cr and 4 kinds of macro elements as K, Na, Ca, Mg were present in both the noninfected and infected mosquitoes. Comparing the contents of the elements between the noninfected and infected mosquitoes, the amounts of many kinds of elements reduced obviously in mosquitoes infected with microfilaria. The quantity and kinds of elements reduced in mosquitoes with the days of infection, for instance, 10 kinds of elements on the 5th day, 11 on the 8th day, 9 on the 12th day and 7 on the 18th day after infection (Tables 1, 2).