Abstract: Objective: To study the relationship between the expression of p65gene of nuclear transcription factor kappa B (NF-κ B) and its suppressor gene-Iκ Bαand in the occurrence of esophageal squamous cell carcinoma. Methods: The expressions of p65 mRNA of NF-κ B and Iκ Bαm RNA were detected using RT-PCR and the p65 protein of NF-κ B and Iκ Bαprotein were detected by S- P immunohistochemical method in specimens of 61 cases of esophageal squamous cell carcinoma and the nor-mal and paraneoplastic epithelial mocosa. Results: The positive counts (the brightness value of band) ofthe expression of p65 mRNA and Iκ BαmRNA were significantly higher in cancer tissues than that innormal epithelium tissues (P<0.01). The positive rates of p65 protein and Iκ Bα protein in plasm or nu-clear in cancer tissues was significantly higher than that in normal epithelium tissues yet (P<0.01).Inthe tumor-adjacent mucosa,the positive rates of p65 protein and Iκ Bα protein expression in plasma ornucleus in the normal esophageal epithelium was significant lower than that in mild and severe atypical hyperplastic epithelium, carcinoma in situ and infiltrated carcinoma. There was a significant differencebetween the normal epithelium and the mild and severe atypical hyperplastic epithelium, carcinoma insitu and infiltrated carcinoma (P<0.05). Conclusion: The expressions ofp65 mRNA and protein of NF-κ B,Iκ Bαm RNA and protein may be correlated with the occurrence of esophageal squamous cell carcinoma.