Abstract: Objective :To study the expression of nuclear factor kappa B (NF-kappa B) in non-small cell lung cancer (NSCLC) and to explore apoptotic ratio of NSCLC with different expression ofNF-kappa B, and the function of NF-kappa B on apoptosis in NSCLC. Methods :Forty-five NSCLCfresh samples were resected from October to December,2005. Expression of NF-kappa B was tested byWestern blot, The apoptotic ratio of NSCLC was detected by Tunel. Results :Of all the 45 patients, theaverage expression of NF-kappa B was 0.604 7± 0.357 2. The expression of NF-kappa B in poorly dif-ferentiated lung cancer cells was higher than that in well-differentiated ones (P<0.05). The apoptotic ra-tio in lung cancer cells with higher NF-kappa B expression was 56.4%, and in those with lower NF-kappa B expression, was 76.7% (P<0.05). Conclusion :Expression of NF-kappa B is related with thedifferentiation of NSCLC. NF-kappa B inhibits apoptosis in NSCLC. As a transcription factor, NF-kap-pa B plays a very important role in the formation and development of NSCLC, and can be a target forgene therapies for NSCLC.