Objective Study the concentration of the hepatocyte growth factor(HGF) the expression product of recombinant human hepatocyte growth factor naked plasmid ,and whether the body generates immune responseafter wsing HCF. Methods Selected 21 patients with severe ischemic disease of lower extremity (Rutherford classification 4-6 class) , after signing the informed consent and divided them into four dosage groups( 4 mg, 8 mg, 12 mg and 16 mg) random.In each group the dosage was the lower limbs partly intramuscular injection following the feeding artery in experimental stage Dl and D15. The plasma samples were collected to determine the HGF concentration in Dl ( before administration), D8, D15 ( before administration) , D21, D59, and the HGF-antibody concentration in Dl, D15, D28, D59, D91. Results (1)The concentrations of HGF in the subjects ranged from 216 pg/mL to 1189.75 pg/mL.(2) HGF-antibodies were not dectected in the subjects' plasma. Conclusions After using recombinant human HGF naked plasmid through intramuscular injection, the concentration of HGF expression product in subjects' peripheral blood does not have abnormally changed and using the drug the human body immune response does not generate.