目的　探讨支气管肺泡灌洗液 (BALF)中K ras原癌基因点突变在周围型肺癌诊断中的价值。方法　应用聚合酶链反应结合限制性片段长度多态性分析法 (PCR RFLP) ,检测 5 4例肺癌及 2 0例肺良性疾病患者支气管肺泡灌洗液中K ras基因第 12位密码子突变的情况。结果　肺癌及肺良性疾病中K ras基因突变率分别是3 5 2 % ( 19 5 4)和 5 0 % ( 1 2 0 ) ,非小细胞肺癌 (NSCLC)突变率明显高于小细胞肺癌 (SCLC) ,其中以肺腺癌突变率最高 ( 47 6% )。突变的发生与肿瘤TNM分型无关。结论　BALF中K ras基因突变的检测对肺癌有一定的早期诊断价值 ,可以协助纤维支气管镜提高对周围型肺癌的诊断率 ,尤其是对肺腺癌 Objective To investigate the value of k ras proto-oncogene mutation in the diagnosis of peripheral lung cancer in bronchoalveolar lavage fluid (BALF). Methods Polymerase chain reaction (PCR) and restriction fragment length polymorphism (PCR RFLP) were used to detect the mutation of the 12th codon of K ras gene in bronchoalveolar lavage fluid in 54 lung cancer patients and 20 benign lung disease patients Happening. Results The rates of K ras gene mutation in lung cancer and benign lung diseases were 35.2% (19 5 4) and 50% (10 2%) respectively. The mutation rates of non-small cell lung cancer (NSCLC) were significantly higher than those of small cell lung cancer ), Of which the highest rate of lung adenocarcinoma mutation (47 6%). The occurrence of the mutation has nothing to do with the tumor TNM typing. Conclusion The detection of K ras gene mutation in BALF has some early diagnostic value for lung cancer, which can help to improve the diagnosis rate of peripheral lung cancer by fiberoptic bronchoscopy, especially for lung adenocarcinoma