Several studies have been conducted to investigate the anti-cancer effects of vitamin C (VC). However, the effect of high-dose VC administration on tumor angiogenesis remains unclear. Focusing on our high-dose VC, our study investigated the effect of high-dose VC (4 g/kg) on vascular endothelial growth in mice with xenografts of a rectal cancer cell line referred to as Colon 26. Male mice harboring Colon 26 tumors were established, and high-dose VC solution was orally administered once daily for 14 d. On the final day of the study, the lower limb tumor tissues and serum samples were collected and analyzed for the expression of tumor angiogenesis related proteins as well as the levels of reactive oxygen species (ROS). Oral VC administration decreased tumor volumes and increased p53 and endostatin levels. In addition, plasma and in tumor part ROS levels and tissue hypoxia inducible factor-1α (HIF-1α) were reduced by VC administration. In addition, the levels of vascular endothelial growth factor A (VEGFA) and vascular endothelial growth factor D (VEGFD) were decreased by VC administration. These results suggest that VC exerts its anti-cancer effects by suppressing angiogenesis.