The purpose of the study was to investigate the effect of nursing care based on Orem's nursing theory on nutritional self-care of myocardial infarction patients. Self-efficacy was explored as a disposition which may motivate behavioral change. One hundred and four subjects were randomly assigned to treatment or control groups. The nursing intervention, which took place during the first 6 weeks following hospital discharge, was effective in supporting healthy low-fat eating behavior. Nursing care influenced patients' self-care agency but lacked impact on self-efficacy for healthy eating.