[en] Objective: To study the effect of human lactoferrin on the X-ray Radiation Injury in mice. Methods: The mice were randomly divided into three groups: control group, radiation group and lactoferrin group. To give mice 6.8 Gy, observe mice' 30 d survival rate and to give mice 2 Gy, observe bone marrow micronucleus, nuclear cell count. Results: All the mice of radiation group without Lactoferrin died in 25 d after exposure. The group the 30-day livability is high, there was a significant difference in comparison between radiation group without lactoferrin and groups with lactoferrin (P<0.05). In the group without lactoferrin, the bone marrow karyocytes decreased significantly after radiation, and the treatment groups (including prevention and emergency) are higher than pure radiation group, there was a significant difference in comparison between radiation group without lactoferrin and groups with lactoferrin (P<0.05). Simply after radiation for 3 days, mice micronucleus bone marrow cells showed a significantly higher rate, and the group without lactoferrin, it showed less than the group with lactoferrin, with significant difference (P<0.05). Conclusion: Lactoferrin which is used in the prevention iron or emergency to has radioprotective effect. (authors)