Pulmonary complications are fatal adverse events after allo-HCT. On the other hand, smoking is a well-known risk factor for various pulmonary diseases and also increases the incidence of pulmonary complications and overall mortality in allo-HCT recipients. In this study, we retrospectively assessed the impact of smoking intensity on survival outcomes. This study included consecutive allo-HCT recipients at our center between June 2007 and May 2019 whose smoking profiles were available (n = 408); they were divided into high (pack-years > 10, n = 171) and low pack-years groups (pack-years ≤ 10, n = 231). In univariate analyses, non-relapse mortality (NRM) and overall survival (OS) were significantly inferior in the high pack-years group (1y-NRM 26.6% vs 13.9%, P <0.001, 1y-OS 58.4% vs 70.1%, P = 0.0067). However, this association was not observed in multivariate analyses. In subgroup analyses according to gender, the survival outcomes in the high pack-years group were significantly inferior in males (NRM HR 2.24 (95% CI: 1.23 - 4.07), P = 0.0082; OS HR 1.54 (95% CI: 1.04 - 2.28), P = 0.031), but not in females (NRM HR 0.587 (95% CI: 0.241 - 1.43), P = 0.24; OS HR 0.689 (95% CI: 0.400 - 1.19), P = 0.18). In summary, high pack-years was associated with inferior survival of allo-HCT recipients, especially in males.Copyright © 2020. Published by Elsevier Inc.