1) The antibody titer of complement-fixation test increased in proportion to the length of incubated time. 2) The antibody titer of complement-fixation test incubated at 0°C. for 6 hours was nearly equal to that of precipitin ring test. 3) The antibody titer of complement-fixation test incubated at 37°C. is higher than that at 0°C. in cardiolipin antigen system, but in yeastmannan system at 0°C. it proves higher than that at 37°C.