Background. This study compared the effects of a formal exercise conditioning program of 3 and 12 months duration to spontaneous recovery in a population of older, post-coronary event patients. Methods. Indices of peak exercise and submaximal exercise performance such as oxygen consumption, treadmill work capacity, minute ventilation, heart rate, and systolic blood pressure were assessed before and after conditioning in 60 post-myocardial infarction and post-coronary bypass surgery patients (mean age 68 ± 5 years) and compared to measures of fitness in a usual care control group (n = 23, mean age 68 ± 5 years). Results. Maximal treadmill work capacity increased by 47% in the intervention group at 3 months compared to no improvement in the usual care control group. However, both groups increased peak oxygen consumption similarly at 3 and 12 months, increasing by 16% and 20% in the intervention group at 3 and 12 months and by 7% and 14% in the control group (p = n.s.). Only the exercise training group manifested submaximal indices of conditioning such as a lower heart rate and minute ventilation at a standard workload. Conclusion. While spontaneous improvements in peak oxygen consumption are seen in older coronary patients in the months following a coronary event, a formal exercise training program results in significantly greater increases in peak exercise capacity and in peak and submaximal exercise efficiency.