Dynamic intraventricular obstruction is a less well-known mechanical complication of acute myocardial infarction (AMI). Its hallmark is the development of a new systolic murmur, and echocardiography is necessary for diagnosis. We describe a case of a 74-year-old woman with dynamic intraventricular obstruction complicating AMI. Serial echocardiography suggested that the intraventricular gradient was a consequence of basal hyperkinesis, which was a reciprocal response to akinesis of the apical wall. Cilostazol, which was administered to prevent subacute stent thrombosis after percutaneous coronary intervention, might have contributed to the transient intraventricular obstruction.