OBJECTIVE: To evaluate the efficacy of Liangxue Guyuan decoction(凉血固元汤, LGD) on radiation-induced intestinal injury in rats, and the possible underlying mechanism of action.METHODS: A total of 255 male Sprague-Dawley rats were used. 15 rats were assigned to the control group and the remaining 240 rats were exposed to a60 Co source at a dose of 11 Gy. Irradiated rats were randomly divided into model, dexamethasone(DXM), low-dose LGD(LGDl), and high-dose LGD(LGDh) groups and treated for 11 d. The survival rate, weight of body, intestinal pathology and the expression of toll-like receptor 4(TLR4), myeloid differentiation primary response 88(MyD88), and nuclear factor-kappa B(NF-κB) were recorded.RESULTS: Radiation reduced the survival rate and weight of rats, destroyed the intestinal structure, induced an inflammatory reaction, and increased both protein and m RNA expression of TLR4,MyD88, and NF-κB in ileum. However, LGDh increased the survival rate, inhibited weight loss, alleviated inflammation and improve the expression of TLR4 pathway.CONCLUSIONS: LGD increased the survival rate and inhibit weight loss of irradiated rats, and reduced inflammation and intestinal injury. The underlying mechanism may involve regulation of the TLR4/MyD88/NF-κB pathway.