A cardiopulmonary exercise test provides information regarding appropriate exercise intensity, but there have been few reports on its use in patients over 80 years of age. Retrospective observational study. A total of 511 cardiovascular disease patients who performed a cardiopulmonary exercise test from February 2011 to January 2020 were investigated. Patients were stratified according to age: < 70 years, 70-79 years, and ≥ 80 years, and the results of the cardiopulmonary exercise test up to anaerobic threshold were compared. Patients in the < 70 age bracket showed higher oxygen consumption, carbon dioxide output, and ventilatory volume and lower ventilation equivalents per oxygen consumption and carbon dioxide output in all time periods. However, there were no significant differences in these parameters or the work rate (70-79 years of age: 41.4 ± 11.7 watts, vs ≥ 80 years: 42.2 ± 10.9 watts, p = 0.95) or oxygen consumption per body weight at anaerobic threshold (12.2 ± 0.2 ml/min/kg, vs 12.1 ± 0.4 ml/min/kg, p = 0.97) between the 70-79 year age bracket and the ≥ 80 year age bracket. Even for cardiovascular disease patients age ≥ 80 years, a cardiopulmonary exercise test up to anaerobic threshold can supply useful information for guiding cardiac rehabilitation.