The effects of γ-rays irradiation on CD3, CD4, CD8, B7.1 molecules expression of human lymphocytes which were irradiated with 0.5, 2, 4 and 8Gy γ-rays or with 0.5, 2, 4 and 8Gy (,D,2,) γ-rays 4h after 10cGy irradiation ,(D,1,), were investigated in normal donor. 24h or 48h after final irradiation the changes of CD3,+, CD4,+, CD8,+, B7.1,+, molecules were measured by flow cytometry(FCM) with immunofluorescence technique. The results showed that the CD3,+, CD4,+, CD8,+, molecules expression in the highly irradiated groups decreased with dose increase, while the CD3,+, CD4,+, CD8,+, molecules privously exposed to 10cGy irradiation could reduce this influence, and the B7.1,+, molecule expression in the high dose irradiation groups was enhanced with increasing dose.