Abstract: Objective 　To discuss the expression of FHIT (fragile histidine triad) gene in lung carcinoma tissues and cell, its promoter methylation, and analyze the relationship among them. Methods 　FHIT mRNA expression was measured by real-time reverse transcription polymerase chain reaction in 45 lung carcinoma, 23 lung side-carcinoma tissues and A549 cell lines. The promoter methylation was determined by methylation-specific PCR(MS-PCR) . Results 　FHIT mRNA were all shown in 23 lung side-carcinoma tissues and the loss frequency was 48. 89 %(22/45) in lung carcinoma. The mRNA expression level of FHIT was significantly lower in lung carcinoma than in lung side-carcinoma tissues ( t = - 15. 851 、P <0. 001) . And in the A549 cell lines, the mRNA expression level of FHIT was significantly higher after dealt with 5-Aza-CdR. However, it was not correlated with the clinical data, such as sex, age, pathological type and tumor size ( P > 0. 05) . While the f requency of promoter methylation of Promoter of FHIT gene was 40. 00 % in lung carcinoma and 8. 70 % in lung side-carcinoma tissues (χ² = 7. 184 、P < 0. 01) .Among 18 patients with aberrant promoter methylation, 10 cases showed the gene inactivation. Conclusion 　Frequency of promoter methylation of Promoter of FHIT gene is apparently higher in lung carcinoma tissues than in lung side-carcinoma tissues, and the expression level of FHIT is either lost or lower in lung carcinoma than in lung side-carcinoma tissues. It may contribute to the function in occurrence and development of lung carcinoma.