Objective:To detect the clinicopathologic characters of micrometastasis and microvessel density(MVD) occur in non-small cell lung cancer(NSCLC),and to explore the correlation among the former factors and those cases with vascular invasion. Methods:Vascular invasion and MVD was recorded by immunochemistry staining to CD34. Blood samples from 47 patients were examined for CK19 mRNA expression by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Results:Serum CK19 mRNA positive was recorded in 13/18 cases with vascular invasion versus 9/29 in cases without invasion,with statistically difference. The average MVD in the invasion group was (29.3 ± 3.3),higher than the non-invasion group(25.2 ± 4.7). Conclusion:CK19 mRNA positive,pleura invasion,lymphnode state,metastasis and MVD are significantly correlated with vascular invasion in NSCLC patients,and these factors could be used to assess biological behavior of NSCLC.