Abstract: Growth dynamics of PP, CN and ZS2 strains of Toxoplasma gondii isolated in China was studied and compared with that of RH strain. HeLa cells were used in this work. It took only 2 min for the organisms of RH strain to infect the HeLa cells when con-tacting with the cells. By contrast, the CN strain requires 5 min, the ZS2 and PP strains, 10 min.Tcxoplasma began its multiplication after a lag time of about 6 h in the HeLa cells. The mean generation time of the 4 strains was assessed by calculating the number of the parasites in the parasitophorous vacuoles at different incubation times and by the linear regression equation. The results showed that the mean generation time was 5.2 h for RH strain, 5.98 h for CN strain, 6.78 h for ZS2 strain and 7.69 h for PP strain.Among the 3 strains of Toxoplasma gondii isolated in China, CN strain was similar to RH strain in their infectivity and proliferation.