The purpose of this study was to investigate the effects of Acceptance and Commitment Therapy on cognitive emotion regulation strategies, Anxiety, Depression, headache disability and headache intensity among patients with chronic daily headache. The study is one-centered, non-blinded, and two-grouped. The population of this study is comprised of all adults with chronic daily headache, referring to the neurology clinic of the Shahid Beheshti Hospital of Kashan City, during 2016. A total of 40 patients selected as the study sample and assigned into intervention and control groups by block randomization method (20 participants in each group). Inclusion criteria include having chronic daily headache according to the International Classification of Headache Disorders, 3rd edition; informed consent to participate in the study and having old above 18. Major exclusion criteria include unwillingness to continue participation; having a medical diagnosis of organic brain disorder or psy-chotic disorder, having a history of psychological treatment during the preceding six months. The intervention group was trained for eight 90-min weekly group sessions. Cognitive emotion regulation Questionnaire (CERQ), Depression anxiety stress scale (DASS-21), Diary scale for headache and Headache related disability inventory (HDI) have administered at pretreatment and post-treatment in both groups. By comparing the mean scores of the two groups, the effectiveness of Acceptance and Commitment Therapy on cognitive emotion regulation strategies, Anxiety, Depression, headache disability and headache intensity determines in patients with chronic daily headache.