Background Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, aggressive hematologic malignancy arising from plasmacytoid dendritic cells. It commonly presents as skin lesions with or without bone marrow, lymph node or systemic involvement. Limited retrospective data have shown durable remissions after allogeneic (allo) hematopoietic cell transplantation (HCT). Methods In this retrospective single-center analysis, we evaluated outcomes of17 BPDCNpatients treated with allo-HCT between September 2000 and August 2019 at our institution. Results We identified 17 consecutive patients who received an allo-HCT for BPDCN. Patient characteristics are summarized in the attached table. Four (23%) had prior hematologic malignancies (HM). Nine (59%) had a cytogenetic abnormality at baseline, and 5/15 (33%), who were evaluated by a Next-generation Sequencing (NGS) Leukemia Mutation Panel, had TET2 mutation. Median time from diagnosis to HCT was 6.7 months (4-42). Median follow up was 7.8 (1.1-76.1) months. One-hundred day and 1-year non-relapse mortality (NRM) was 6% and 35%, respectively. Grade 1-2 acute GVHD was seen in 5/16 (31%), and limited or extensive chronic GVHD in 4/16 (25%) evaluable patients. Only two of the 17 (12%) allo-HCT patients progressed after HCT. Two-year PFS and OS was 48% (95% confidence interval=20%, 72%) and 56% (26%, 78%), respectively. Patients receiving allo-HCT in CR1 without prior HM had significantly better PFS (71% vs. 0%; p=0.020) and OS (71% vs. 0%; p=0.036). Conclusions These results demonstrate the safety and efficacy of allo-HCT inBPDCN. Patients undergoing allo-HCT in CR1 and without prior HM had significantly better outcomes. Prospective studies are needed to better define the role of allo-HCT inBPDCN.