Abstract: In this paper a modified humoral immune assay method is described, The basicprinciple is as follows:The lymphocytes of animas immunized With sheep erythrocytes can produce hemolysin, which is released to circulating blood. The serum of sensitized animal is separated. When it is incubated with sheep erythrocytes, hemolytic phenomenon appears at 37℃ after addition of complement. The quantity of hemolysin in the serum of sensitized animal is measured by the amount of released hemoglobin during hemolysis.This method is more simple, fast and exact.The assay procedure and some results of well known drugs are presented.