Background & aim: Stress in any physical illness makes its symptoms worse. Hypertension is a common illness that psychological factors such as stress can worsen its symptoms and complications; the present study aimed to evaluate the effectiveness of Roy's adaptation model on alexithymia and diet adherence in people with hypertension comorbid with stress. Methods: This was a quasi-experimental study with a pretest-posttest design and a control group. Using the convenience sampling method, 40 patients with hypertension comorbid with stress (21 females and 19 males) who were referred to Aligudarz city medical centers in 2021, were selected by convenience sampling method and randomly assigned to the experimental (n=20) and control (n=20) groups. The experimental group received a Roy's adaptation model intervention for 8 sessions of 60 minutes, but the control group did not receive any intervention. The data were collected by the stress, anxiety and depression questionnaire, Toronto emotional dysfunction scale, diet information record form and a form for assessing Roy's adaptation model. Results:The results of covariance analysis showed that Roy's adaptation model was significantly effective in reducing alexithymia (F=235.24, p<0.01) and increasing diet adherence (F=540.87, p<0.01) in hypertension patients comorbid with stress. Conclusion:The results of this study suggest that Roy's adaptation model significantly decreased the alexithymia and increased diet adherence, therefore using Roy's adaptation model in hypertension patients comorbid with stress is recommended.