Background and Purpose: Diabetes has adverse effects on the quality of life of patients. Roy's adaptation model could be used to enhance quality of life among diabetic patients. This study aimed to evaluate the effects of Roy's adaptation model in nursing practice on the quality of life in patients with type II diabetes.Methods: This quasi-experimental study was conducted on 60 diabetic patients randomly divided into two groups of experiment and control (N=30) at Hamadan Diabetes Research Center. Data were collected using Diabetes-Specific Quality of Life Scale (D-39) in five dimensions, which was completed before and after intervention in both groups. Educational care programs were executed based on Roy's adaptation model only for experimental subjects in five sessions during one month. Data analysis was performed using independent and paired t-test in SPSS. Results:At the beginning of the study, both groups were matched in terms of demographic characteristics and quality of life dimensions (P>0.05). Comparison of mean scores of quality of life areas between the two groups before and after intervention was indicative of a significant difference in the aspects of diabetes control, energy and mobility and social support (P<001). However, there was no significant difference in the dimensions of stress, anxiety and sexual activity (P>0.05). Conclusion:According to the results of this study, use of Roy's adaptation model has positive effects on some dimensions of quality of life in patients with type 2 diabetes; these domains were diabetes control, energy and mobility, and social support. However, further studies with longer durations are required as to investigate the efficacy of this model in the areas of anxiety and sexual activity.