Over a period of 6 years, 52 patients with acute myocardial infarction (AMI) were treated with sequenced external counterpulsation (SECP). Of the 23 patients who experienced severe chest pain, 22 had complete relief within 30 min of SECP, and 31 of the 52 patients showed remarkable improvement in their electrocardiogram after the first hour of treatment. Fifteen patients were studied using the 35-lead ST segment elevation-mapping method. sigma ST and NST, indicators of infarct size, showed decreasing trends in seven patients treated with SECP for a period of 6 days, whereas sigma ST and NST of the control group of eight patients increased during the same period. Our hemodynamic data indicate that in four of five patients with AMI and left heart failure, the central venous pressure and cardiac output increased after SECP, whereas the pulmonary wedge pressure decreased. Measurements of the P-wave terminal force of lead V1 also demonstrated that the application of SECP can improve left ventricular function in a majority of patients with AMI.