Study aim: This Study Purpose is determine the effectiveness of mindfulness based stress reduction Treatment on psychological disturbance, intensity of pain and burning, Pain Catastrophizing and Quality of Life of Patients with Oral Lichen Planus. Design: Clinical Trial with Control Group, with Parallel Group, Single Blind, Randomized, on 50 Patients Settings and conduct: Dental clinics affiliated with Kashan University of Medical Sciences and Department of Oral and Dental Diseases of Tehran University of Medical Sciences, Patient who have the Inclusion Criteria are Selected And after Obtaining Informed Consent, they will be Randomly Placed in Experimental and Control Groups Also, before the Implementation of the Intervention, Questionnaires will be Provided to them. The Participants are not Given Information about which of the Groups is the Experimental and which of them is Control Group. Participants/Inclusion and exclusion criteria: Inclusion Criteria: Oral Lichen Planus Patients whose Disease has been Diagnosed through Biopsy and Histopathology Results and who are in the symptomatic phase of the disease. Non Inclusion Criteria: Absence of Pain and Burning or Mild Pain and Burning (Score Lower than 4 on the VAS), Age younger than 18 and older than 60, Degree less than middle School degree Intervention groups: Experimental Group: Mindfulness Based Stress Reduction is implemented for them. Control Group: Training Sessions about Some Topics of Developmental Psychology or Personality will be Provided that are not Related to the Main Intervention. Main outcome variables: Psychological Disturbance Score in DASS-21, Pain Catastrophizing Score in Pain Catastrophizing Scale