In order to study the effects of rhIL−11 on radiation gamages to bone marrow cells in mice induced by 4.0Gy neutron irradiation, 96 BALB/c male mice were treated with rhIL−11 by subcutaneous injection 3 d before or after 4.0Gy total body irradiation (TBI) with neutrons. The peripheral blood cells and bone marrow nuclear cells were counted. The proliferation and apoptosis of bone marrow cells were evaluated by AgNOR staining, flow cytometry and DNA gel electrophoresis, respectively. The expressions of IL−11Rαand gp130 were studied by immunocytochemistry and image analysis. After the irradiation, the peripheral blood cells, content of AgNOR and expressions of IL−11Rα and gp130 decreased obviously. However, the trends of WBC, PLT were suppressed in the group treated with rhIL−11 before the irradiation, and the trends of WBC, RBC, PLT were suppressed in the group treat with rhIL−11 after the irradiation. In both the treated groups, the content of AgNOR and expressions of IL−11Rα and gp130 are higher than those in control group. But there was not significant difference in apoptosis. IL−11 may play a positive role against injuries to bone marrow by promoting the reconstruction of bone marrow after the irradiation through IL−11Rα and gp130 signaling.