Recently, we have reported that surgical stress promoted the metastasis of murine colon carcinoma cells to the lung by inducing the expression of proteases such as matrix metalloprotease-9 (MMP-9) in lung tissue. Urinary trypsin inhibitor (UTI) is a serine protease inhibitor frequently used to treat pancreatitis and to improve the microcirculatory environment. The purpose of this study was to investigate the anti-metastatic properties of UTI in an animal model of surgical stress-induced cancer metastasis. The intraperitoneal administration of UTI after the intravenous injection of colon 26-L5 carcinoma (colon 26-L5) cells into mice subjected to surgical stress suppressed the enhancement of lung metastasis (p<0.05). Furthermore, we investigated the effect of UTI on tumor growth, adhesion to fibronectin, migration, invasion and enzymatic degradation in colon 26-L5. UTI reduced the invasive ability and the degradation by MMP-9 of gelatin substrate in colon 26-L5 cells. UTI may improve therapeutic efficacy in cancer patients after major surgery.