Background:Patients’ beliefs about the cause of cardiac disease (perceived risk factors) as part of the global psychological presentation are influenced by patients’ health knowledge. Hence, the present study aimed to assess the relationship between actual and perceived risk factors, identification of underestimated risk factors, and indication of underestimation of every risk factor.Materials and Methods:In this cross-sectional study, data of 313 coronary artery bypass graft (CABG) patients admitted to one hospital in the west of Iran were collected through a demographic interview, actual risk factors’ checklist, open single item of perceived risk factors, and a life stressful events scale. Data were analyzed by means of Spearman's correlation coefficients and one-sample Z-test for proportions.Results:Although there are significant relations between actual and perceived risk factors related to hypertension, family history, diabetes, smoking, and substance abuse (P < 0.05), there is no relation between the actual and perceived risk factors, and patients underestimate the role of actual risk factors in disease (P < 0.001). The patients underestimated the role of aging (98.8%), substance abuse (95.2%), overweight and obesity (94.9%), hyperlipidemia (93.1%), family history (90.3%), and hypertension (90%) more than diabetes (86.1%), smoking (72.5%), and stress (54.7%).Conclusion:Cardiac patients seem to underestimate the role of aging, substance abuse, obesity and overweight, hyperlipidemia, family history, and hypertension more than other actual risk factors. Therefore, these factors should be highlighted to patients to help them to (i) increase the awareness of actual risk factors and (ii) promote an appropriate lifestyle after CABG surgery.