Immunologically mediated aplastic anemia in mice were used as animal models to study the the curative effect of Zaizhang-I in term of the changes of two pathogenetic aspects in aplastic mice, namely the deficiency of hematopoietic stem cells and the disturbance of immunology. Our results demonstrated that in aplastic mice, after treatment by Zaizhang-I, the loss of mature hematopoietic cells (WBC, RBC, Plt) were reduced, and marrow cellular cytosis, and their clinical findings were improved, indicating a partial remission. The present data show that its curative mechanism lies in the action of promoting the recovery of colony forming unit-spleen (CFU-S) and reversing immunologically-induced plasma colony forming unit granulocyte/macrophage (CFU-GM) inhibitory activity. Natural killer cells activity (Nka) and interleukin-2, tumor necrosis factors (TNF) were also so examined to further understand the mechanism by which Zaizhang-I reverse plasma hematopoietic activity.