Abstract: Objective: To compare three methods of detecting Toxoplasma-gondii-infected-cells in culture and to explore a better one for pathogenic diagnosis of toxoplasmosis.Methods: The Toxoplasma tachyzoites were added in the Hela cell and THP-1 cell culture system,then the infected cells were counted at different times(3 to 9 hours) by light microscope with the Giemsa staining,by fluorescence microscope with IFA,and by flow cytometry(FCM).Results: The infection rates of Hela cells examined by Giemsa staining and by IFA were 22.0‰ and 24.3‰ respectively,and the infection rate of THP-1 cells examined by FCM was 42.0‰(P<0.05). Conclusions: The detection rate of affected THP-1 cells is the highest by FCM,while it is similar by IFA or Giemsa staining.