Recombinant human TPO (rhTPO) promotes platelet engraftment in patients after allogeneic HSCT (allo-HSCT). However, the effects of rhTPO on platelet recovery after Haplo-HSCT in patients with severe aplastic anemia (SAA) have not been intensively studied.We aimed to evaluate the efficacy of rhTPO on platelet engraftment in patients with SAA who were treated with Haplo-HSCT using post-transplantation cyclophosphamide (PTCy).SAA patients who received Haplo-HSCT plus PTCy regimen were divided into the rhTPO group (with subcutaneous injection of rhTPO, n=28) and Control group (no rhTPO administration, n=27). The engraftment of platelet/neutrophil, platelet infusion amount, and transplant-related complications between the two groups were compared.All 55 patients showed successful hematopoietic reconstitution. The median time of platelet engraftment was 11 (9-29) days in the rhTPO group and 14 (9-28) days in the Control group (P=0.003). The rhTPO group had a significantly reduced amount of infused platelets compared to the Control group (2 (1-11.5) vs 3 (1-14) therapeutic doses; P=0.004). There was no significant difference between the two groups regarding median time of neutrophil engraftment, incidence of acute graft-versus-host disease (aGVHD) and chronic GVHD (cGVHD), incidence of cytomegalovirus or Epstein-Barr virus reactivation, 3-year overall survival rate, and failure-free-survival rate. No obvious adverse reactions were observed in the rhTPO group.rhTPO promoted platelet engraftment, reduced the amount of transfused platelets, and demonstrated good safety profiles without evidence of adverse reactions in patients with SAA who received Haplo-HSCT using PTCy regimen.Copyright © 2024. Published by Elsevier Inc.