Bronchiolitis obliterans syndrome (BOS) after allogeneic hematopoietic SCT (HSCT) is recognized as a new-onset obstructive lung defect (OLD) in pulmonary function testing and is related to pulmonary chronic GVHD. Little is known about the different phenotypes of patients with BOS and their outcomes. We reviewed the data of all allogeneic HSCT recipients referred to our pulmonary department for a non-infectious bronchial disease between 1999 and 2010. We identified 103 patients (BOS (n=77), asthma (n=11) and chronic bronchitis (n=15)). In patients with BOS, we identified two functional phenotypes: a typical OLD, that is, forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio <0.7 (n=53), and an atypical OLD with a concomitant decrease in the FEV1 <80% and FVC <80% predicted with a normal total lung capacity (n=24). The typical OLD was characterized by more severe FEV1 and fewer centrilobular nodules on the computed tomography scan. The FEV1 was not significantly affected during the follow-up, regardless of the phenotype. In addition to acute and extensive chronic GVHD, only the occurrence of BOS soon after transplantation and the intentional treatment of BOS with steroids were associated with a poor survival. The determination of patient subgroups should be explored to improve the management of this condition.Bone Marrow Transplantation advance online publication, 3 December 2012; doi:10.1038/bmt.2012.241.