A sandwich ELISA was established with monoclonal antibody as detecting antibody and rabbit anti-Toxoplasma polyclonal antibody as capturing antibody. ABC (avidin-biotin-peroxidase complex)-ELISA and immuno-PCR were also used to detect different concentrations of Toxoplasma antigen. The lowest concentration of antigen to be detected by sandwich ELISA, ABC-ELISA and immuno-PCR was 0. 6 microg/ml, 0. 075 microg/ml and 0.1 ng/ml respectively. The immuno-PCR shows a much higher sensitivity than the other two methods.