Abstract BACKGROUND: Cardiac rehabilitation is a well-established treatment for patients with coronary artery disease and it is beneficial for cardiac patients. It improves functional capacity and modifies risk factors of coronary artery disease such as hypertension, arrhythmia and others. The aim of this study was to investigate the effects of cardiac rehabilitation on functional capacity of patients after cardiac surgery by using the six-minute walking test which is a simple and well-tolerated test for cardiac patients compared with other stress tests. METHODS: Thirty two patients were selected for this study. All patients had cardiac surgery, two months before admission. These samples allocated to two groups. Interventional group (n = ۱۷, mean age: ۶۲ ± ۱۲ years) completed the cardiac rehabilitation programs for two months but, reference group (n = ۱۵, mean age: ۵۸.۵ ± ۱۲.۵ years) didn't have any physical activity during this period. At the beginning of study, functional capacity of patients was evaluated by exercise test and six-minute walking test. After two months of cardiac rehabilitation, functional capacity was evaluated for the second time in each group. Cardiac rehabilitation consisted of exercise, nutritional and psychological consultation and risk factor management. Data were analyzed with SPSS software version ۱۵. For comparing the mean of outcomes in repeating measures, the repeated ANOVA model was used. RESULTS: A Significant improvement was observed in the interventional group compared to the reference group in walking distance (۴۷۲.۶۲ ± ۱۹.۲۹ m vs. ۴۱۲.۲۴ ± ۲۰.۵۴ m, respectively, P = ۰.۰۴). CONCLUSION: Cardiac rehabilitation significantly improves functional capacity and this evolution was shown by ۶MWT which is an easy and safe and low cost test compared to other stress tests. Keywords: Cardiac Rehabilitation, Functional Capacity, Stress Test.