Free-floating thrombus of the ascending aorta is a rare disease entity which carries a potential risk of distal embolization with catastrophic consequences. We present the case of a 46-year-old patient with floating thrombus in the ascending aorta, likely caused by catheter injury, after a percutaneous coronary angiography with stent implantation at the circumflex artery and no antiplatelet agents. A 46-year-old female patient was admitted to the emergency room with acute chest pain radiating to the left arm for the past 3 days. She reported a history of cigarette smoking and a ST-elevation myocardial infarction with stent implantation at the level of the circumflex artery about 1 month before. The patient was not taking any antiplatelet therapy for explicit refusal. Transthoracic echocardiography showed an isoechoic lesion in the ascending aorta and no other abnormalities of the cardiac structure and function and of the valve systems. Transoesophageal echocardiography confirmed the presence of a coarse (17 mm 14 mm) isoechoic formation, with a large base of implantation at the level of the non-coronary aortic cusp, extending approximately 45 mm into the aortic vessel with a floating attitude (Panels A–C). Computed tomography angiography showed a pedunculated mass measuring 22 mm 22 mm 45 mm in ascending aortic lumen (Panels D and E). Intact intima and normal size of ascending aorta with no signs of aortic dissection or intramural haematoma were also reported. The patient underwent a thrombectomy (Panel F) and aortic replacement. A histopathologic examination revealed the mass to be a fibrin thrombus. The post-operative course was uneventful. No recrudescence or concomitant visceral or vascular embolism was observed. The patient was discharged with dual antiplatelet agents.