Rh-Endostatin (Endostar; Simcere Pharmaceutical Co., Ltd, JiangSu,China) is a humanized recombinant endostatin which is a direct angiogenesis inhibitor targeting the microvascular endothelial cells (ECs). A pivotal phase III study completed in China demonstrated that the addition of rh-endostatin to navelbine plus cisplatin conferred clinically significant improvements in overall survival (OS), progression-free survival (PFS), as well as response rate (RR), in patients with previously untreated metastatic non small cell lung cancer (NSCLC). In vitro, the combination of Endostatin and fluorouracil showed synergistic activity in inhibiting colon cancer. MFolfox6 was standard first-line regimen in advanced colorectal cancer. The investigators carried out a phase II trial to investigate the activity and safety of rh-endostatin plus mFOLFOX in patients with metastatic colorectal cancer.