To examine the relationship between the levels of the serum vascular endothelial growth factor (VEGF) and the micrometastasis of peripheral blood in patients with non-small cell lung cancer (NSCLC), 108 NSCLC patients, including 40 patients with benign lung diseases and 30 healthy controls, were investigated. The serum VEGF levels were detected by ELISA and CK19 mRNA in peripheral blood by reverse transcriptase-polymerase chain reaction (RT-PCR). In NSCLC group, the serum VEGF levels and the positive rate of CK19 mRNA in peripheral blood were 479.8+/-268.5 pg/mL and 66.7%, which were significantly higher than those of the other two groups respectively (P<0.01), and both of them were increased significantly with the progression of clinical stage of the tumors (P<0.01). Serum VEGF levels as well as the positive rate of CK19 mRNA in different pathological types of lung cancer had no significant differences (P>0.05). Serum VEGF levels in the patients positive for CK19 mRNA was 561.7+/-325.6 pg/mL. It is significantly higher than that in the negative patients (P<0.01). There existed a significant correlation between serum VEGF levels and expression of CK19 mRNA in peripheral blood in NSCLC patients (P<0.001). The detection of serum VEGF levels and CK19 mRNA in peripheral blood is helpful in judging the condition and the prognosis of NSCLC patients, and serum VEGF levels and CK19 mRNA are independent of the pathological types of lung cancer. The micrometastasis in peripheral blood of NSCLC patients is significantly associated with serum VEGF levels.