Tumor growth and metastasis depend on vessel formation, and inhibition of angiogenesis of tumor by production of anti-angiogenic drugs should be a promising approach for cancer therapy. Tumstatin is an angiogenesis inhibitor. The anti-angiogenic activity of tumstatin is localized to the 54-132 amino acids. The gene fragment encoding amino acids 45-132 of tumstatin (tum-5) was subcloned into pcDNA3.1 (pcDNA-tum5). Tum-5 protein could be expressed and secreted in CHO cells after transfection. The conditioned medium (containing tum-5 protein) from the transfectant has an anti-angiogenic effect on HUVEC cells in vitro. The anti-tumor effect of pcDNA-tum5 on mice bearing S180 tumors was evaluated. The results showed that pcDNA-tum-5 has a significant inhibition activity in the growth of the tumors. This study suggests that the gene delivery of tum-5 may be an effective strategy for cancer therapy.