Background: Coronary artery disease (CAD) is a chronic disease. These patients need a high level of illness perception and self-care behaviors until the end of their lives. Objectives: The present study aimed to examine the effect of the teach-back method on illness perception and self-efficacy in patients with CAD. Methods: This quasi-experimental study was conducted on 100 patients with CAD hospitalized in the coronary care units (CCUs) of Zahedan University of Medical Sciences in southeast Iran in 2021. The patients were selected through convenience sampling and divided into two intervention and control groups using simple randomization. The self-care training program was implemented individually for the patients in the intervention group in three sessions (30 - 45 minutes) on three consecutive days 24 hours after the patient’s admission to the hospital. The Brief Illness Perception Questionnaire (Brief IPQ) and Cardiovascular Management Self-efficacy Scale (CMSES) were completed by the patients in the two groups before and one month after the intervention. The collected data were analyzed in the statistical package for the social sciences (SPSS v.22) software using the independent samples t-test, paired samples t-test, chi-square test, Fisher’s exact test, regression test, and analysis of covariance (ANCOVA) at a significant level of P < 0.05. Results: In pre-test, the two groups had no significant difference in the mean score of illness perception (P = 0.49). However, the mean score of self-efficacy was significantly higher in the intervention group (P = 0.01). In the post-test, the two groups had significant differences in both illness perception (P = 0.002) and self-efficacy (P = 0.001). The results of ANCOVA showed that by controlling the effect of the pre-test, the mean scores of illness perception (P < 0.001) and self-efficacy (P = 0.007) were significantly different between the two groups after one month of the intervention. Conclusions: The teach-back method improved illness perception and self-efficacy in patients with CAD. Thus, following the insights from this study and given the vital role of nurses in patient education, nurses and medical staff can use the teach-back method to improve illness perception and self-efficacy in these patients.