Objective: To investigate radioprotective effect of laminaria japonica polysaccharides (LJP) and its possible mechanism. Methods: The Wistar rats were randomly divided into 6 groups, the normal group, the model group and four LJP treatment groups(100,200,300 and 400 mg·kg -1 ·d -1 ). LJP of four different doses was applied to different group respectively for 10 d before whole body irradiation with γ ray(9.0 Gy). The indexes of humoral immune, cellular immune, nonspecific immune functions and apopt...