Introduction: Chronic pain is annoying and this may cause reduction of the patient's tolerance threshold. Patients suffering from chronic pain experience significant psychological symptoms. This study was aimed to investigate the effectiveness of behavioral-cognitive treatment on decreasing pain intensity in patients suffering from chronic pain. Materials and Methods: The sample of 30 patients diagnosed with chronic pain were divided into two groups, including 14 men and 16 women. Pain intensity evaluation questionnaire was used to collect data, the pre-test, post-test, and follow-up of both control and experimental groups were completed. Behavioral- cognitive treatment was performed during 8 sessions. Results: This study revealed that the mean pain intensity scores in post-test significantly decreased compared to pre-test values. Conclusion: Our results indicated that cognitive-behavioral treatment is effective on decreasing pain intensity in patient suffering from chronic pain.