Objective: To investigate the immunological mechanism of extract of grifola frondosa on spleen deficiency mice. Method :Thirty Kunming mice were randomly divided into 6 groups:control group

spleen deficiency group

positive control group and three groups with dosage difference(5

10 and 20 mg ·kg-1 ).After the establishment of spleen deficiency

the treatment of the extract and the positive drug was lasted for 10 days(ip).Then phagocytosis of peritoneal macrophages was detected by neutral red;NO-producing ability was determined by Griess method;and lymphocyte transformation rate

NK cell activity were tested by MTT method. Result: Extract of grifola frondosa could increase the above mentioned ability. Conclusion: Extract of grifola frondosa can enhance the ability of macrophages and the production of NO

and the lymphocyte transformation rate

NK cell killing activity to improve immunological ability of spleen deficiency in mice.