Objective: To analyze the relationship of Stat3 expression with clinical stages, tissue types, p53and proliferation cell nuclear antigen (PCNA) in human lung carcinoma, and to evaluate the role of Stat3 in the pathogenesis of lung carcinoma. Methods: Immunohistochemical method were used to detected Stat3,p53 and PCNA in different tissues of patients (n= 42) with lung carcinoma who accepted neither radiotherapy nor chemotherapy. Results: The positive rate of Stat3 was 81.0% in lung carcinoma and its expression level was related to the tissue type but not to T, N or the clinical stage. The expression level of Stat3 in non-small cell lung carcinoma (NSCLC) was higher than that in small cell lung carcinoma (SCLC). A positive correlation of the expression of Stat3 with that of p53 and PCNA was identified. Conclusion: The expression level of Stat3 is abnormal in lung carcinoma. Stat3 may be involved in the regulation of p53 gene in lung carcinoma cell, it may accelerate the proliferation of lung carcinoma cells and play an important role in the pathogenesis of lung carcinoma.