BACKGROUND Coronary ostial stenosis is a life-threatening complication of aortic valve replacement (AVR). Clinical symptoms usually appear within the first 6 months after AVR (Funada and Mizuno et al., Circ J 70:1312-7, 2006), and perioperative onset is very rare. METHODS An 80-year-old woman with severe aortic stenosis was scheduled to undergo AVR. AVR using cardiopulmonary bypass (CPB) was successfully carried out. However, 5 min following AVR, signs of left heart failure appeared, and transesophageal echocardiography (TEE) revealed severe hypokinetic left ventricular wall motion. Left coronary ostial stenosis was diagnosed by TEE, and CPB was immediately resumed and coronary artery bypass grafting (CABG) to the left anterior descending branch was performed. CONCLUSIONS When circulatory failure presents in the acute phase following AVR, onset of coronary ostial stenosis should be considered.