The objective of the study was to investigate angiogenesis in non-small lung cancer by measuring the expression of CD34. Immunohistochemistry was used to detect CD34 at the endothelial cell surface in 81 surgically resected non-small cell lung cancer specimens. CD34 immunohistochemistry had high specificity and sensitivity with minimal background, which enabled efficient identification of CD34-positive staining. Statistical analysis showed that increased microvessel density (MVD) was closely correlated to tumor progression as reflected by the clinical stage (P < 0.05). However, MVD was not significantly associated with lymph node metastasis and other clinical and pathological features (P > 0.05). In conclusion, microvascular density may play an important role in the development and progression of lung cancer.