Objective: To study the effect of panax notoginsenosides (PNS) on the proliferation of hematopoietic progenitor cells (HPC) in mice with immune-mediated aplastic anemia. Methods: Balb/c mice model of immune-mediated aplastic anemia was established by radiation with sublethal dose of 60 Co following the intravenously infusing lymphocytes of DBA/2 mice. Model mice in the treated groups were treated separately with high, middle and low dose of PNS, 3.2mg, 1.6 mg and 0.8 mg per day respectively by intraperitoneal injection. Model mice in the control group and normal mice in the normal control group were treated with normal saline. The peripheral white blood cell (WBC) count and pathological examination of bone marrow were carried out 12 days later, the bone marrow was taken to be incubated in semi-solid culture system for observing proliferation of HPC. Results: PNS could (1) increase peripheral WBC count: as compared with that in the model control, WBC in the high, middle and low dose PNS groups was raised by (34.3±2.9)%, (29 2±1 7)% and (14 5±1 6)% respectively, P<0 01 and P<0 05; (2) improve the bone marrow inhibition: pathological examination showed in the model group, the hematopoietic structure was destroyed and replaced by fatty tissue, while in the PNS treated groups, the structure of marrow was rather complete and filled with abundant hematopoietic cells; (3)promote the proliferation of HPC: as compared with the model group, the colony formation of CFU-GM were increased by (64 4±2 8)%, (67.3±2.4)% and (21.9±1.8)% respectively and that of CFU-E increased by (31.9±3.6)%, (20.7±2.4)% and (12.8±2.6)% respectively in the three PNS treated group (P<0 01 and P<0 05). Conclusion: PNS could enhance hematopoiesis by promoting proliferation of CFU-GM and CFU-E progenitors so as to improve the hematopoietic function in mice of immune-mediated aplastic anemia.