Objective\ Transferrin receptor(TfR) is one of important membrane receptors expressed in T cells stimulated with antigens or mitogens and is closely related with the activation and proliferation of T lymphocytes. Researches on radiation effects of TfR expression have not been reported yet. Studying the change and function of TfR expression after high dose ionizing radiation is important for clarifying the mechanism of ionizing radiation inhibiting immune function. Methods TfR expressions in lymphocytes in mouse spleens in different doses and at different time after the whole body irradiation (WBI) with X rays were examined using flow cytometry. Results At 24 hours after the WBI with 0.5-6 Gy X rays, TfR positive splenocytes decreased with the increasing irradiation dose beginning at 1Gy and showed dose dependent reduction. From 12 to 72 hours after WBI with 4 Gy X rays TfR positive splenocytes started reducing at 12 hours after WBI and reached the nadir values at 24 hours and 48 hours ( P<0.05,P<0.01) , and began to recover from 72 hours after WBI. Conclusion High dose ionizing radiation inhibits the TfR expression in splenocytes of mice and there is an obvious dose dependency. The decrease of TfR expression may be related to the inhibition of IL 2 production and IL 2 receptor expression in cells by radiation.