Objective To investigate the synergism and attenuation effects of Pini Pollen on cyclophosphamide chemotherapy in model mice.Methods The models of mouse were induced with S180 tumor and cyclophosphamide. The tumor inhibiting rates, hematology, Liver function, giant cell phagocytosis, hemolysin level and indexes of thymus and spleen were determined to evaluate the synergism and attenuation effects of Pini Pollen(150,300,600 mg/kg) on cyclophosphamide chemotherapy.Results Compared with cyclophosphamide chemotherapy group,the tumor inhibiting rates,white blood cell number,giant cell phagocytosis, hemolysin level and indexes of thymus and spleen were increased, at the same time liver function damage were alleviated significantly in cyclophosphamide plus Pini Pollen groups. Conclusions Pini Pollen has a remarkable synergism and attenuation effects on cyclophosphamide chemotherapy through its immune adjustment functions.