Introduction: Psychological therapies can play an essential role in the improvement of anxiety, depression, and stress in patients with asthma. The purpose of this study was to investigate the effectiveness of cognitive-behavioral stress management group therapy in group therapy on anxiety, depression, stress, and re-admission in asthmatic patients. Methods: In this quasi-experimental study, 38 patients with asthma were selected and randomly assigned to intervention and control groups. DASS-21 questionnaire was used for data collection, which was completed at pre-test, post-test, and follow-up. Cognitive-behavioral stress management therapy was administered to the intervention group on ten sessions, eight but no intervention conducted for the control group. Data were analyzed using ANCOVA, one-way ANOVA, t-test, and repeated measures. Results: The results showed that there was a significant difference between the mean score of depression in the intervention group before (6. 42 ± 7. 9) and after the intervention (5. 05 ± 5. 55) (P = 0. 00). There was also a significant difference between the mean score of depression between the response (5. 05 ± 5. 55) and control groups (13. 47 ± 9. 49) in the first month (P = 0. 017). There was a significant difference between the mean scores of stress before (10. 74 ± 5. 97) and after (9. 05 ± 5. 22) the intervention in the intervention group (P = 0. 00). The mean score of the anxiety variable after the response was a significant difference between the intervention group (4. 53 ± 5. 37) and control groups (10. 95 ± 7. 90) (P = 0. 01). There was no significant difference in re-admission in the intervention and control groups before and after the intervention. Conclusions: The results of the present study indicate the effectiveness of cognitive-behavioral stress management therapy in improving anxiety, depression, and stress in patients with asthma. Also, results showed the high level of anxiety, depression and stress in patients with asthma and the effectiveness of cognitive-behavioral stress management training intervention and the need for serious attention to psychological therapies in this group of patients.