Introduction: Long-term survival after allogeneic hematopoietic cell transplantation (alloHCT) is limited by chronic pulmonary graft-versus-host disease (cGvHD) which comprise classical bronchiolitis obliterans (BO), but also various forms of restrictive disease. Histological confirmation of BO by transbronchial forceps biopsy has a low sensitivity and surgical lung biopsy is gold standard. The clinical diagnosis of BO syndrome (BOS) is based on lung function and radiological data. However, sensitivity of BOS-criteria for biopsy-proven BO is unsatisfactory. Aim: Retrospective study to investigate the diagnostic value of transbronchial cryobiopsy in alloHCT-patients with suspicion of pulmonary cGvHD not fulfilling BOS-criteria. Histology was integrated into the multidisciplinary discussion (MDD) and diagnostic consensus was sought. Results: 20 patients underwent cryobiopsy. In 13/20 patients (65%) cryobiopsies revealed findings leading to a specific diagnosis: obliterative/lymphocytic bronchiolitis in four (20%), distinct parenchymal abnormalities leading to the diagnosis of interstitial lung disease (ILD) or cGvHD-associated ILD in 9/20 patients (45%). In 7/20 patients (35%), cryobiopsies showed normal lung parenchyma. In 4/7, a consensus diagnosis of BOS was reached after MDD. Complications of cryobiopsy included pneumothorax (25%) and locally controlled bleeding (20%). Conclusion: In alloHCT-patients with suspicion of pulmonary cGvHD not fulfilling BOS-criteria, transbronchial cryobiopsy led to a histology-based diagnosis in two-thirds of patients, and ? embedded in an MDD - to a final diagnosis in 90% of patients.