Haemoptysis is a life-threatening complication of cystic fibrosis (CF). One treatment is bronchial artery embolisation (BAE) using embolic-microspheres (EMs). During BAE, pulmonary arteries can be seen on digital subtracted angiography while iodine containing contrast material injection is performed in the bronchial artery. This suggests that EMs could go from bronchial to nontarget pulmonary arteries. The aim was to evaluate if EMs could be found inside pulmonary arteries on lung explants after BAE in transplanted CF patients.Retrospective observational study including patients with CF who underwent lung transplantation and had previously needed BAE. Clinical, chest CT angiography, and angiographic data were reviewed from medical records. Pathology examination of lung explants was performed to analyze the EMs anatomical localisation.Eight patients were included between 2013 and 2015, four males with a mean age of 29 (19-45) years. All patients had bronchial artery hypertrophy on CT and bronchial-to-pulmonary artery shunting during BAE. On pathology examination, EM ≤800 µm were found in the pulmonary arteries in all patients and were responsible for distal branch occlusions. Two pulmonary infarcts were observed on CT angiography after BAE and confirmed histopathologically.EM migration from the bronchial to pulmonary arteries is a common occurrence after BAE in patients with advanced stage CF. Although BAE is a highly effective means of controlling haemoptysis in CF, studies on the optimal particle size are needed to preserve pulmonary artery circulation, because these results suggest that low size EMs could lead to nontarget embolisation.