The aim of the study is to examine high-intensity interval training (HIIT) programs and a moderate-intensity continuous training (MICT) program, which are frequently used in cardiac rehabilitation programs in terms of their effects on the functional capacity and quality of life of patients with coronary artery disease (CAD). The study included 20 patients with CAD (mean age, 60.95 ± 5.08 years) who had undergone revascularization surgery. The participants were randomized into HIIT-short, HIIT-long, and MICT groups. All the groups participated in a 24-session exercise-based cardiac rehabilitation program. The participants’ exercise capacity was evaluated using the maximal exercise test and estimated VO 2max values, functional capacity using the 6-min walk test (6MWT), and quality of life using the Short Form-36 survey and MacNew Heart Disease Health-related Quality of Life (MacNew) questionnaire. It was determined that the estimated VO 2max values statistically significantly improved after treatment ( P < 0.05), and both HIIT groups were superior to the MICT group ( P < 0.05). Only the HIIT groups achieved the minimal clinically important difference in the 6MWT distance. After treatment, only the MICT group had a statistically significant improvement in quality of life. There was no statistically significant difference between the groups in relation to the improvement in the 6MWT distance and quality of life ( P > 0.05). The results of our study showed that both HIIT programs were superior to MICT in improving the maximal exercise capacity of patients with CAD, and the three programs had a similar effect on quality of life.