BACKGROUND In this case report we describe an extremely rare case of cerebral air embolism following transbronchial lung biopsy (TBLB). Only a few cases of this rare complication were described previously. Every bronchologist should recognize this severe adverse event. Prompt recognition of this complication is mandatory in order to initiate supportive measures and consider hyperbaric oxygen therapy. CASE SUMMARY In this case report we describe an extremely rare case of cerebral air embolism following TBLB. Only a few cases of this rare complication were described previously. Our patient had an incidental finding of lung tumour and pulmonary emphysema. Cerebral air embolism developed during bronchoscopy procedure, immediately after the third trans-bronchial lung biopsy sample and caused cerebral ischaemia of the right hemisphere and severe left-sided hemiplegia. Despite timely initiation of hyperbaric oxygen therapy hemiplegia didn´t resolve and the patient died several weeks later. Cerebral air embolism is an extremely rare complication of TBLB. This condition should be considered in case the patient remains unresponsive or presents with acute neurological symptoms in the post-intervention period since early recognition, diagnosis and hyperbaric oxygen therapy initiation are key factors determining the patient´s outcome. CONCLUSION Within this report, we conclude that air/gas embolism is an extremely rare complication after TBLB, which should be considered in case the patient remains unresponsive or presents with acute neurological symptoms in the post-intervention period after bronchoscopy. The current gold standard for diagnosis is computed tomography scan of the head. After recognition of this complication we suggest immediate hyperbaric oxygen therapy, if available. Background: In this case report we describe an extremely rare case of cerebral air embolism following transbronchial lung biopsy (TBLB). Only a few cases of this rare complication were described previously. Every bronchologist should recognize this severe adverse event. Prompt recognition of this complication is mandatory in order to initiate supportive measures and consider hyperbaric oxygen therapy. Case summary: In this case report we describe an extremely rare case of cerebral air embolism following TBLB. Only a few cases of this rare complication were described previously. Our patient had an incidental finding of lung tumour and pulmonary emphysema. Cerebral air embolism developed during bronchoscopy procedure, immediately after the third trans-bronchial lung biopsy sample and caused cerebral ischaemia of the right hemisphere and severe left-sided hemiplegia. Despite timely initiation of hyperbaric oxygen therapy hemiplegia didn´t resolve and the patient died several weeks later. Cerebral air embolism is an extremely rare complication of TBLB. This condition should be considered in case the patient remains unresponsive or presents with acute neurological symptoms in the post-intervention period since early recognition, diagnosis and hyperbaric oxygen therapy initiation are key factors determining the patient´s outcome. Conclusion: Within this report, we conclude that air/gas embolism is an extremely rare complication after TBLB, which should be considered in case the patient remains unresponsive or presents with acute neurological symptoms in the post-intervention period after bronchoscopy. The current gold standard for diagnosis is computed tomography scan of the head. After recognition of this complication we suggest immediate hyperbaric oxygen therapy, if available.