Background and Aim: Heart failure is a chronic disease that affects the physical and psychological aspects of life. Psychological adaptation of patients needs follow-up and training. The purpose of this study was to determine the effectiveness of an educational program based on Roy adaptation model on the psychological adaptation in patients with heart failure.Materials and Methods: This clinical randomized trial was performed on 60 patients with heart failure admitted in Vali-e-Asr Hospital and Heart Research Center in Birjand in 2013. The patients were selected through the convenience sampling and randomly allocated to an intervention group and a control group (30 individuals in each group). The data was collected using Roy assessment form and Mental Health Inventory (MHI-38) whose reliability are confirmed in previous studies. The content validity of the Mental Health Inventory was first confirmed. Later, in order to check for its reliability, it was given to 20 individuals for which Chronbach's alpha was 0.91. The intervention group received an educational program based on maladaptive behavior and stimuli which was followed by a follow-up period of one month. The control group received the regular service. The data were analyzed in SPSS (version 15) using independent t test, paired t test, Mann Whitney, Wilcoxon, Fisher Exact Test, and Chi square.Results: Mean scores for maladaptive behaviors and the number of maladaptive behaviors showed no significant differences before the intervention, while the difference was significant after the intervention in the two groups (p<0.001). In the intervention group, the dimensions that had significant decrease included physiological (p<0.001), self-concept (p<0.001), interdependence (p<0.004), and role function (p<0.001). The psychological adaptation scores mean significantly increased in the intervention group (p<0.001). However, there was no significant difference in the control group in the different dimensions (p>0.05).Conclusion: Using an educational program based on Roy adaptation model can be effective on the psychological adaptation and reduction of maladaptive behaviors in patients with heart failure. In this regard, nurses can play a more effective role in improving the psychological adaptation of patients using the educational program.