Abstract : Purpose: This study aimed to identify the correlation between aerobic threshold (AT) and cardiopulmonary response at the start of exercise in patients with myocardial infarction (MI). Subjects and Methods: Thirty-one male patients with MI underwent a sub-maximal cardiopulmonary exercise test with expiratory gas analysis to determine their peak oxygen uptake (VO2) level, using Ramp protocol. Results: The patients demonstrated an extended time constant (TC) and decline in AT in this study. Extended TC suggested impaired cardiac function due to reduced left ventricular ejection fraction (LVEF), as well as an LVEF of 52.8% on average. However, there was no significant correlation between TC and AT. Pearson product-moment correlation coefficients were 0.56 between AT and area under the oxygen uptake curve (VO2AUC), -0.22 between TC and VO2AUC, and -0.23 between AT and TC. Conclusion: VO2AUC is representative of oxygen utilization and is correlated with AT in patients with MI.