objective: to assess the correlation between neoplastic microvessel density (mvd) and a series of pathological characteristics and study the prognostic value in postoperative patients of thymic epithelial tumors. methods:mvd in 66 cases of thymic epithelial tumor was evaluated by the expression of monoclonal cd34 antibody. survival analysis of 62 patients with 16~178 months follow-up was calculated using the kaplan-meier method and differences in survival were analyzed using the log rank test. results:there were no significant correlation between mvd and some pathological characteristics including the patients’ age (p > 0.05) and gender (p > 0.05). although bigger tumor (≥11.0 cm) developed higher mvd value,no significant difference was found compared with smaller tumor(<11.0 cm). mvd values were significantly different among subtypes of who histological classifications(p < 0.05)and clinical stages of masaoka’s staging system(p < 0.01). no positive correlation was found between mvd value and the status whether the patients had paraneoplastic myasthenial gravis or not(p > 0.05). the survival curves showed that the increased mvd,who histological classifications and masaoka’s staging system were valuable prognostic predictors of thymic epithelial tumors. conclusion:tumor angiogenic activity might play an important role in capsular and widely neighbouring invasion of thymic epithelial tumors. mvd together with who histological classifications and masaoka’s staging system seem to be more helpful for clinical prognostic estimation.