Aim: Heart failure is a progressive, debilitating disease with exacerbated physical and psychological symptoms that reduces the quality of life of patients. Nursing intervention based on nursing theories could help in the adaptation of patients to the disease and improving quality of life. The aim of this study was to determine the effect of an educational program based on Roy's adaptation model on the quality of life of patients with heart failure. Methods and Material: In this randomized controlled trial, 76 patients with heart failure were allocated to either the intervention or control group through a blocked randomization method. The data were collected between May and October 2017. The intervention group received oral and written educational programs for 4 weeks. Minnesota quality-of-life questionnaire and Roy's adaptation model-based evaluation form was completed at the beginning of the trial, and 1 month after the completion of the study. Results: Intervention patients showed statistically significantly improved scores on the physiologic, role function, independence-interdependence dimensions and the total score of Roy's adaptation model over time compared with control patients (p < .05). The mean score of all of the three quality-of-life dimensions and total score of quality of life increased significantly (p < .05). Conclusion: The study results help nursing staff detect the stimuli and the behaviors of patients with heart failure. Roy's adaptation model can be used as a standard practice to increase adaptation to the disease and improving quality of life. K E Y W O R D S adaptation, heart failure, quality of life, Roy's adaptation model