To investigate the relationship between tumor angiogenesis and hematogenous metastasis in colorectal cancer, an immunohistochemical analysis using antibody against factor VIII was carried out on archival specimens of 35 primary tumors. In addition, we also evaluated the levels of vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8), by an enzyme-linked immunosorbent assay (ELISA), in tumor specimens and the serum in the drainage venous blood. The levels of VEGF showed no correlation with the microvessel density and also did not increase significantly in patients with hepatic metastasis. On the other hand, the IL-8 levels in the tumor tissue (r=0.45) and the serum IL-8 levels (r=0.49) showed a significant correlation with the microvessel density. The serum IL-8 levels in patients with Dukes' C colorectal cancer and hepatic metastasis were significantly higher than in those without hepatic metastasis (p<0.05). In addition, the serum levels of IL-8 in patients with Dukes' C cancer without hepatic metastasis and those with Dukes' A and B cancer were also closely similar. These results suggest that IL-8 is associated with the microvessel density in primary tumors and thus play an important role in the occurrence of hepatic metastasis in patients with colorectal cancer. As a result, elevated levels of IL-8 in the drainage vein are considered to be a useful predictor for developing hepatic metastasis in patients with resectable colorectal cancer.