Different p120ctn isoforms exert different, even opposing, effects on tumor cell growth depending on the level of E-cadherin expression, but the impact on clinicopathological parameters of lung cancer patients is not clear. Herein, we investigate the correlation between pan-p120ctn, p120ctn isoform 1, and E-cadherin expression and clinicopathological parameters, especially prognosis, of lung cancer patients. Immunohistochemistry on 20 specimens of normal bronchial epthelium revealed that, p120ctn isoform 1 was not expressed at the membrane; only weak cytoplasmic expression was seen. In contrast, both pan-p120ctn and E-cadherin were expressed clearly on the cell membrane or in the cytoplasmic peri-membrane region. However, in squamous cell lung cancer or lung adenocarcinomas, p120ctn isoform 1 over-expressed in the cytoplasm accompany with the abnormal pan-p120ctn and E-cadherin cytoplasm expression. p120ctn isoform 1 over-expression correlated positively with lymph node metastasis, poor differentiation, histological type, and high TNM stage. Cytoplasmic p120ctn isoform 1 expression in metastatic nodules was always higher than in the primary tumor. While the mean survival times of patients with normal p120 ctn isoform 1 or pan-p120ctn expression differed significantly, the mean survival times of patients with abnormal expression were similar. Lymph node metastasis, TNM stage, abnormal pan-p120ctn expression, and p120ctn isoform 1 over-expression were all independent factors affecting the prognosis of lung cancer patients. Over-expression of p120ctn isoform 1 positively correlated with poor prognosis of lung cancer patients, and therefore may be a useful marker of lung cancer patient survival.