目的　探讨CA12 5Ⅱ检测对肺癌的辅助诊断和疗效观察的价值。方法　采用IRMA法 ,对 90例肺癌患者和 2 0例肺良性疾病患者血清CA12 5Ⅱ检测。结果　各组肺癌CA12 5Ⅱ水平均显著高于肺良性疾患组和正常对照组 (P <0 0 5及P <0 0 1) ;其阳性检出率分别是鳞癌 36 1% ,腺癌 71 4% ,未分化癌 41 7% ,对整体肺癌的敏感性为 5 3 3% ,特异性为 95 0 % ,其阳性检出率与临床分期有关 ,Ⅲ、Ⅳ期明显高于Ⅰ、Ⅱ期 (P <0 0 1)。结论　CA12 5Ⅱ测定对肺癌特别是肺腺癌的诊断有较高的价值 ,是临床分期 ,疗效观察以及预后判断的重要参考指标 Objective To investigate the value of CA12 5 Ⅱ in the diagnosis and treatment of lung cancer. Methods The IRCA method was used to detect serum CA12 5 Ⅱ in 90 patients with lung cancer and 20 patients with benign lung disease. Results The levels of CA12 5 Ⅱ in lung cancer were significantly higher than those in benign lung disease group and normal control group (P <0.05 and P <0.01). The positive rates of CA12 5 Ⅱ were 36 1% in squamous cell carcinoma and 71 4 in adenocarcinoma %, 41.7% of undifferentiated carcinoma, 533% of the overall lung cancer sensitivity and 95% specificity, the positive detection rate and clinical stage, Ⅲ, Ⅳ was significantly higher than Ⅰ, Ⅱ ( P <0 0 1). Conclusion The detection of CA12 5 Ⅱ is of great value in the diagnosis of lung cancer, especially in lung adenocarcinoma. It is an important reference index for clinical staging, curative effect observation and prognostic judgment