Anti-alpha-chymotrypsinogen A antibody was assayed by both enzyme-linked immunosorbent assay (ELISA) and liposome immune lysis assay (LILA). The detection limit was slightly affected by the measurement conditions in ELISA; however, it was possible to control the detection limit and to achieve a lower level by adapting the measurement conditions in LILA. LILA is believed to offer a simple and highly sensitive method for measuring the concentration of antibody in serum.