In brief: This study describes the influence of highly intense aerobic circuit training on the cardiorespiratory fitness of 31 coronary artery disease (CAD) patients who had undergone bypass surgery. The patients trained at 84.2% of heart rate (HR) reserve three times a week for 12 weeks. Duration per session progressed from 25 to 60 minutes over the first six weeks. Results showed that the subjects improved significantly in estimated peak mets, percent body fat, resting HR, HR and rate pressure product (RPP) response to standard submaximal exercise (7.2 mets), and maximal RPP. In addition, there were no abnormal responses related to cardiovascular or musculoskeletal complications. Thus, this type of exercise is an effective, safe, and attractive cardiorespiratory training method for CAD patients following bypass surgery.