Objective To explore the feasibility of gene therapy for human tumors by direct injection of recombinant plasmids. Methods Mouse tumor model was established by transferring human ovarian carcinoma (SKOV 3) tissues or separated cells subcutaneously into the oxter of nude mice, with a successful rate of 100%. The coding region for human endostatin (hES) fused with the signal peptide sequence of human growth hormone was amplified by PCR from a commercial recombinant plasmid and the correctness of the hybrid gene was confirmed by sequence analysis following subcloning into pGEM-T vector. The hybrid gene was subcloned into a eukaryotic expression vector pcDNA3 and its expression in COS-1 cells was demonstrated by immunofluroscence. Results Significant inhibition of the tumor growth was observed in 6/6 mice after muscular injection of nude mice with established tumor with pcDNA-ES. When the injection was done before tumor transplantation, the tumor could not establish itself in five out of the eight mice, while established in all of the mice (4/4) without plasmid injection. Conclusion These data indicate that the {established} animal model and gene therapy strategy might be useful for further studies on treating human tumors.