A 91-year-old man was admitted to our hospital with dyspnea and chest pain. His electrocardiogram showed ST-segment elevation in the V_(1-4) Ieads, and an emergency coronary angiogram revealed subtotal occlusion in the left descending coronary artery. A successful primary percutaneous coronary intervention was subsequently performed using aspiration thrombectomy and bare metal stent implantation. However, his hemodynamic condition deteriorated with severe pulmonary congestion. Administration of inotropes with diuretics and mechanical ventilation were not effective, and an echocardiogram showed coexisting severe aortic stenosis. As a bailout procedure, we performed balloon aortic valvuloplasty (BAV) with a 12- and 14-mm balloon on the next day. After BAV, the patient's condition improved, and he was weaned from the ventilator. It is commonly understood that onset of acute myocardial infarction may trigger worsening of heart failure in patients with compensated aortic stenosis. However, emergency balloon aortic valvuloplasty, when timely administered, is considered a simple and effective procedure for such patients, and can lead to substantial clinical improvement.