Abstract: The changes in the contents of free amino acids in hemolymph of Anopheles stephenst were determined by automatic amino acid analyzer.The changes in hemolymph protein were determined by ultraviolet absorption method.Free amino acids in hemolymph of infected mosquitoes were compared with those in noninfected mosquitoes.At 4 days after blood meal,6 kinds of amino acids decreased markedly,and 5 kinds of amino acids increased markedly; at 7 days after blood meal,4 kinds of amino decreased markedly,while 7 kinds of amino accids increased markedly; at 11 days after cids blood meal,9 kinds of amino acids decreased markedly,and 4 kinds of amino acids increased remarkably.The protein concentration of infected mosquitoes was higher than that of noninfected ones.