en Aim: Continuous physical activity is required after coronary artery bypass graft (CABG) surgery to prevent recurrence of the disease; however, its amount is not suitable in many patients. The present study aimed to investigate the stages of physical activity in patients after CABG using the Trans-Theoretical Model (TTM).<br />Methods: In this cross-sectional research, 120 cardiac patients participated; they had CABG surgery and referred to Ekbatan Hospital of Hamadan. Sampling was conducted using a purpose-based approach. Data were collected using a researcher-made questionnaire based on the TTM and analyzed using the SPSS18 software. Descriptive statistics and statistical processes of one-way ANOVA, Tukey's post-hoc, and Chi-square tests were also conducted at a significant level of p<0.05.<br />Findings: The mean age of the participants was 57.87±9.89 years. From the 120 patients under study, 4.2% were in the pre-contemplation phase, 14.2% in the contemplation stage, 58.3% in the preparation stage, 10.8% in the action stage, and 12.5% in the maintenance phase of the physical activity. The results of ANOVA test showed a significant difference between the stages of change in behavior with perceived advantages, perceived disadvantages, perceived self-efficacy, and processes of change (p <0.001).<br />Conclusion: The results showed that many patients did not have regular physical activity after surgery. This makes clear the need for educational interventions based on theoretical models by health educators. Physical Activity,Coronary artery bypass graft surgery,Trans-theoretical Model 23 36 http://hehp.modares.ac.ir/browse.php?a_code=A-5-21630-1&slc_lang=en&sid=4