Objective: To compare the immunomodulatory effects of spore polysaccharides (Gl-SP) and broken spore polysaccharides (Gl-BSP) isolated from Ganoderma lucidum(Leyss et Fr.) Karst. on murine splenic lymphocytes and peritoneal macrophages in vitro. Methods: Mixed lymphocyte culture reaction (MLR), lymphocyte proliferation in the presence or absence of mitogen, and the cytotoxic activity of splenic natural killer (NK) cells were detected with MTT assay in vitro. The percentage of phagocytosis of neutral red (NR) by mouse peritoneal macrophages was detected by colorimetric assay. Splenic T-lymphocyte subpopulations were measured with flow cytometry(FCM). IL-2, IFN-? and TNF-? in the culture supernatants were detected by ELISA and biological assay. Nitric oxide (NO) production was examined by Griess reaction. Results: At the concentration range of 0.2-12.8 mg/L, Gl-SP and Gl-BSP were shown to increase lymphocyte proliferation in the presence or absence of mitogen, enhance NK cytotoxic activity, augment the production of TNF-? and NO in Gl-SP-or Gl-BSP-activated macrophages, as well the percentage of phagocytosis of NR by macrophages in vitro. Both Gl-SP and Gl-BSP could promote MLR, however, at the dose of 12.8mg/L, Gl-BSP showed higher activity than Gl-SP in the proliferation of lymphocytes. These two kinds of polysaccharide could significantly increase the secretion of IL-2 and IFN-? in double-way MLR at the concentrations of 0.2-12.8 mg/L, but Gl-BSP had stronger effects than Gl-SP at the same concentrations. Both Gl-SP and Gl-BSP could increase the ratio of T-lymphocyte subpopulations in double-way MLR. At the concentrations of 0.2-12.8 mg/L or 3.2-12.8 mg/L, Gl-BSP demonstrated more significant activity in increasing the percentage of the CD4+ or CD8+ subset than Gl-SP. At the concentrations of 0.2-0.8 mg/L, the ratio of the CD4+ and CD8+ subset in the Gl-BSP treated group was higher than that of the Gl-SP treated group. Conclusion:Gl-SP and Gl-BSP have sim-ilar immunomodulatory effects in vitro, as though the immunomodulatory effects of Gl-BSP are stronger than that of Gl-SP.