Objective: To detect the expression of CK-19 mRNA in peripheral blood of non-small cell lung cancer(NSCLC) patients by real-time fluorescence quantitative polymerase chain reaction(RT-QPCR),and discuss the value of the experiment. Methods: The expression of CK-19 mRNA in peripheral blood of 113 NSCLC patients(NSCLC group),50 non-cancer patients and 50 healthy person(control group) was detected using RT- PCR and found out the positive cases. Then,RT-QPCR was used to detect the expression of relative levels of CK-19 mRNA in positive peripheral blood. The accuracy of this trial was analyzed by receiver operating characteristic curve(ROC curve) and the area under ROC curve(AUC). Results: ① The expression rates of CK-19 mRNA in the NSCLC group and the control group were 38.94%(44/113) and 1.00%(1/100),respectively,there was significant difference between them(P < 0.01),and the expression of CK-19 was related to TNM classification and differentiation of cancer. ② The analysis of ROC curve showed that when the point of transition was 0.236,its sensitivity and specificity were 95.45% and 77.27% respectively,and the AUC was 0.896. Conclusion: CK-19 mRNA might be the specific and sensitive marker to detect circulating tumor cells in peripheral blood of NSCLC patients,but it still needs to be proved by further follow-up observation in a large volume sample.