The exact role of thymosin beta10 in lung cancer progression remains unclear. We investigated by immunohistochemistry the expression of thymosin beta10 protein in tumors and tumor-adjacent tissues from 69 patients with non-small cell lung cancer. The relationship of thymosin beta10 expression with vascular endothelial growth factor, vascular endothelial growth factor-C, microvessel density, and lymphatic vessel density was determined; clinicopathologic factors and surgical treatment outcome were also studied. The results showed that thymosin beta10 was mainly expressed in the cytoplasm of lung cancer cells, and the overexpression of thymosin beta10 was correlated with advanced clinical stage (P = .026), distant metastases (P = .016), lymph node metastases (P = .007), poor degree of differentiation (P = .03), and poor postoperative survival (P = .004). Furthermore, thymosin beta10 overexpression was associated with vascular endothelial growth factor (P = .004), vascular endothelial growth factor-C (P = .017), microvessel density (P = .000), and lymphatic vessel density (P = .002). The lowest survival rate was observed in the patients with high thymosin beta10, positive vascular endothelial growth factor, and high microvessel density (P = .007) or in the patients with high thymosin beta10, positive vascular endothelial growth factor-C, and high lymphatic vessel density (P = .005). These results suggest that thymosin beta10 might induce microvascular and lymphatic vessel formation by up-regulating vascular endothelial growth factor and vascular endothelial growth factor-C in lung cancer tissues, thus promoting the distant and lymph node metastases and being implicated in the progression of non-small cell lung cancer.