['An intercostal muscle (ICM) flap is used to buttress the bronchial stump or bronchial anastomosis during thoracic surgery for airway reconstruction. Such flaps sometimes show ossification after surgery. Previous reports have suggested that such ossification requires a functional periosteum and good vascularization. We examined the background of ICM flap ossification and its relationship with complications and pain after surgery.', 'We surveyed the clinical records of 47 patients who underwent bronchial stump reinforcement with an ICM flap during thoracic surgery at Kansai Medical University Hospital between January 2003 and December 2005. We reviewed the post-surgical chest computed tomography (CT) scans of 42 patients, and examined the degree of ICM ossification. We classified patients into two groups: those with ossification of the ICM flap (O group) and those without (non-O group). We compared the two groups for age, gender, the site of ICM flap placement, disease, type of lymph node dissection, and pretreatment. We also compared the two groups for pain levels and complications after surgery. Eight (19%) of the 42 patients showed ossification of the ICM after surgery. There were statistically significant differences between the O and non-O groups in gender (p=0.029), lymph node dissection (p=0.024) and pain levels after surgery (p=0.034). There were no complications attributable to ICM ossification in this series.'] Does ossification cause any complication when a bronchial stump is reinforced with an intercostal muscle flap?