A patient had a fire in his chest cavity during dissection of the left internal mammary artery before coronary artery bypass graft. The electrosurgical unit indirectly ignited gauze, resulting in a fire. It was determined that oxygen was being entrained into the surgical field through open pulmonary blebs. This case identifies the need for continued fire training and prevention strategies, persistent vigilance, and quick intervention to prevent injury whenever electrosurgical units are used in an oxygen-enriched environment.