Abstract: Objective:To study the mechanism and effect of FHIT gene in non-small cell Lung can-cer and to investigate the relationships between FHIT and the clinical data, such as age, gender, smoking, histological type, clinical stage and lympho node metastasis. Methods: Forty cases of NSCLC and normal tissues LOH (loss of heterozygote) of FHIT gene were deteited by PCR-electrophoresis (de-natured polyacrylamide gel)-silver staining and significance of FHIT transformation in NSCLC occur-rence was discussed. Results: The consequence showed that about 70.0% (28/40)displayed LOH in NSCLC group and this was significantly higher compared to the control group (0/40). We also found that 23 cases (82.1%) were the smokers in 28 cases with lung squamous cancer, and 7 (58.3%) were the smokers in 12 cases with lung adenoid cancer. The rate of the smoking patients with lung squamous cancer was higher than those of lung adenoid cancer patients. We also found FHIT gene LOH was related to smoking and histological type, but it was not related to other clinical data. Conclusion: LOH of FHIT gene plays a very important role in carcinogenesis in NSCLC. Smoking is relevant to deficiency rate of the lung squamous cancer and it suggests that the FHIT gene is the carcinogenic target molecule in the cigarette