Abstract: In order to generate cancer vaccine trans fected with GM-CSF gene via recombinant adenoviral (R-Ad5) vectors and to examine the antitumor effect of cancer vaccine, R-Ad5 vectors contain ing the gene for human GM - CSF are used to infect H22 cells, a hepatocellu1ar carcinoma cell line of BALB/c mice origin. GM-CSF production was measured in vitro by enzyme-linked immunosorbent assay (ELISA). Tumorigenicity. of H22 cells trans fected with GM -CSF genevia R-Ad5 vectors was studied.The results showed that R-Ad5, vectors could successfully carry GM -CSF gene into H22 cells and efficiently espress for 26 to 31 days. Irradiation did not abolish secretion of sufficient GM-CSF levels. Secretion of GM -CSF from the tum0r cells abrogated their tumorigenicity. Our resu1ts indicates the feasibility of cancer gene therapy with expression of GM - CSF gene in tumor cell pr0vided a basis for further investigation on cancer vaccine.