Abstract： Objective To investigate expression of inducible nitric oxide synthase, cyclooxygenase-2and Vascular endothelial growth factor in human colorectal carcinoma and their clinical significances. Methods The expressions of COX-2, iNOS, VEGF in 58 casees of colorectal carcinoma tissue were assessed by immuno-histochemistry, and there relation to there clinical significance were statistically analyzed. Results Positive ex-pression rates of COX-2, iNOS, VEGF in 58 casees of colorectal carcinoma tissue were79.31% (46/58)、 84.48% (49/58),79.31% (46/58), which were significantly higher than that in colorectal tissues, the expres-sions of COX-2,iNOS, VEGF donnot relate to age,lymph node status and the structural type of eolorectal carci-noma(P>0.05). The expression of COX-2was correlated with VEGF and iNOS. (P<0.05). Conclusion COX-2,iNOS may promote angiogenesis through the way of VEGF,they may be important biological markers in evaluateing the malignant degree and prognosis.