Abstract: The possibility of treating thrombosis diseases by gene transfer was studied with eukaryotic expression vector containing human mUK cDNA. Thirty Kunming mice were divided into 6 groups. The doses (ip) of pcDNA 3 mUK in group 1—4 were 20, 40, 60, 80 pig/mouse respectively. The other 2 groups were injected intraperitoneally with pcDNA 3 and transfection solution respectively as controls. The plasma mUK activity was measured with synthetic—peptide substrate S 2390. They increased significantly (P＜0.05) in group 2-4 from the 5th to the 60th day after the injection as compared with those before the injection (940±200 IU/L, n=30), and reached the peaks of 2200±220, 3050±340，3350±260 IU/L respectively 10 days after the injection. The result suggests that the method of injection with recombinant plasmid containing human mUK cDNA may be applied to the prevention and treatment of thrombosis diseases.