Flow cytometry analysis method was used to detect the changes of γH2AX protein expression in human peripheral blood lymphocytes. In the dose-effect study, peripheral blood was irradiated by 60Co γ-rays with the dose of 0-6 Gy and cultivated for 1 h. Peripheral blood were cultivated for 0-24 h after 4 Gy 60Co γ-rays irradiation for the time-effect study. Then, the peripheral blood was divided into four treatment groups, i.e. UV irradiation, 60Co γ-rays irradiation, UV plus 60Co γ-rays irradiation and control group to detect the changes of protein expression in different time. The results showed that the γH2AX protein expression was in a dose-dependent form. The expression of γH2AX peaked at 1 h after 4 Gy irradiation and began to decrease quickly. The expression of γH2AX in UV irradiation group increased compared with that of the sham-irradiation control group, and the expression of γH2AX peaked at 6 h. While compared with that of the 60Co γ-rays group, the γH2AX expression of UV combined 60Co γ-rays group was unchanged. The results reveal that the detection of γH2AX protein expression changes in peripheral blood lymphocyte by flow cytometry analysis is reasonable and may turns be a new way for biological dosimeter.Cited