Objective: To study the vascular endothelial growth factor changes before and after the androgen treatment to acute aplastic anemia patients. Methods: One hundred and twenty adults (aged 20-40) and 48(aged 1-14) children with acute aplastic anemia were observed. The changes of blood, bone marrow and vascular endothelial growth factor in serum concentration after medical treatment by androgen were researched. Results: After the androgen treatment to acute aplastic anemia patients, three lines hematopoietic cells increased while lymphatic cells without increasing. Bone marrow hematopoietic increased, excluded megakaryocytes. Because a limited number of megakaryocytes, it was not included in the statistics category. Blood and bone marrow got better and vascular endothelial growth factor increased gradually. The vascular endothelial growth factor in children was higher than that of adults (P<0.05). Conclusion: After androgen treatment vascular endothelial growth factor of the patients with acute aplastic anemia increases gradually, the blood and bone marrow are improved at same time.