Objective To understand the injury mechanism of Vero cells(African green monkey kidney cells) exposing to chloroform(CCl 3)for 24hours.Methods\ The content of reactive oxygen species(ROS) and cytoplasmic Ca 2+ concentration in Vero cells were measured with microfluorometry. Meanwhile, the injury of Vero cells was detected with lactate dehydrogenase(LDH) activity in the supernatant of the medium for Vero cells. Results\ There were no any differences for the above indices between CCl 3 group of 4 0mM concentration and control group statistically( P >0 05). Moreover, there were no any differences in cytoplasmic Ca 2+ concentration of Vero cells between all groups exposing to CCl3 and control group( P >0.05). In the other hand, the contents of ROS in the Vero cells exposing to CCl 3 at 8 0mM and 12 0mM concentration were higher than those in the control group( P <0 01)respectively, and the activity of LDH in supernatant of the medium for Vero cells exposing to CCl 3 at 8 0mM and 12 0mM concentration was higher than that of latter( P <0.05, P <0 01)respectively. Conclusion\ The possible injury mechanisms of Vero cells exposing to CCl 3 of high concentration are partly mediated by increasing the content of ROS in Vero cells.