Abstract: Objective To test the expression of IDO and VEGF mRNA in tumor tissues and para-carcinoma tissues of esophageal squamous cell carcinoma(ESCC)patients and to investigate their associations with tumor invasion and lymphatic metastasis. Methods Carcinoma tissue and para-carcinoma tissue specimens were collected from 56 cases of ESCC patients who underwent esophagectomy in The Fourth Hospital of Hebei Medical University. Optical density semi-quantitative RT-PCR and immunohistochemical method were used to detect the expression of IDO and VEGF mRNA. The association between the expressions of IDO, VEGF mRNA and patients' clinical features were analyzed. Results Compared with para-carcinoma tissues, the expression levels of IDO and VEGF mRNA in ESCC tissues were significantly increased (P=0.020, P=0.022). The expression of IDO and VEGF mRNA were both associated with patients' TNM stage, tumor invasion depth, tumor differentiation and lymph node metastasis (P＜0.05), but age or gender(P＞0.05). Meanwhile the expression of IDO mRNA was positively correlated with VEGF mRNA significantly (r=0.533, P=0.001). Conclusion In ESCC tissues, the expression of IDO and VEGF mRNA are significantly up-regulated. These changes of gene expressions are associated with patients' clinical features, which indicate that they might play a key role in tumor invasion and lymph node metastasis.