Abstract: Objective To investigate promoter methylation , mRNA expression of RASSF1A gene（RAS association domain family 1A）and their correlationship in lung carcinoma. Metholds The promoter methylation status of RASSF1A were detected by methylation-specific PCR（MS-PCR）,mRNA expression level was measured by real-time reverse transcription polymerase chain reaction. Results methylation rate of RASSF1A gene was 53.33%（24/45）in lung carcinoma tissues ,13.04%（3/23）in normal lung tissues（χ2 =10.32 ρ<0.05）. RASSF1A mRNA expressed normally in all 23 normal lung tissues ,whereas, loss expression in the tissues of 28.89%（13/45）lung carcinoma,the mean level of RASSF1A mRNA was significantly lower in lung carcinoma tissues than in normal tissues（t=18.696, ρ<0.05）.However, it was not correlated with clinical data, such as sex, age, pathological type and tumor size. In 24 patients with the aberrant promoter methylation, 13 cases showed loss expression of RASSF1A mRNA. Conclusion Frequency of RASSF1A promoter methylation is apparently higher in lung carcinoma tissues than in normal tissues,the mean level of RASSF1A mRNA expression is also lower in lung carcinoma than in normal tissues. It signify that RASSF1A methylation may contribute to the low expression of RASSF1A and development of lung carcinoma.

Key words: Lung carcinoma, DNA methylation, Polymerase chain reaction, RAS association domain family1 A gene