Background & Objective: Lose a loved person is considered as painful experiences, but most people cope well with their loss and do not need professional help. Their experiences involve feelings of sadness, a deep sense of pain and the perception of their life never being the same compared to before the loss. However, reviews showed that the process of grieving in individuals experience grief after a loss of loved ones may be harder, which can impair their cognitive, emotional and behavioral functioning. This bereavement can be associated with physical decline, mental health problems, change in social roles, cognitive deficits and fewer relationships with others, which make the grieving process more difficult. For some the grieving process may be distorted termed complicated grief, which is a form of chronic grief with intense separation distress related to the loss. The resulting syndrome of complicated grief causes substantial distress and functional impairment even years after a loss, yet knowing when and how to intervene can be a challenge. As a result, grief work will be one of the common challenges that social workers, psychologist and grieved people will face. Providing a mindfulness based cognitive therapy for people with complicated grief can be a benefit for their individual growth in understanding a sense of bereavement and for the purpose of social interconnection. This Therapy will cover bereavement life with a concept of mindfulness and how it can be utilized for people in their day– to– day lives. Overall, the goal for this project for participants was to learn coping skills, gain knowledge in the mechanism of mindfulness during the grieving process and how they can integrate mindfulness principles into their grieving process to better facilitate their coping with their loss. Methods: In the present study, we used multiple baseline experimental single case study design. Three women with complicated grief were selected from patients of counseling service centers by using purposeful sampling method, along with inventory of complicated grief (ICG). This questionnaire describe an emotional, cognitive, or behavioral state associated with complicated grief. The ICG consists of 19 items and answers are given on a 5– point scale ranging from never (0) to always (5). ICG gives a possible range of 0– 76 with high scores indicating high levels of CG. The ICG has shown high internal consistency, test– retest reliability. In this study, Cronbach's alpha was calculated 0. 92. Patients underwent the treatment process subsequent to obtaining treatment requirements. The efficacy of mindfulness– based cognitive therapy was carried out in three phase of intervention (baseline, treatment and follow– up) by using Inventory of complicated grief. In this project, Data analyzed with visuals inspection, improvement percentage and reliable change index (RCI) strategies. In addition, to examine the efficacy of this psychological intervention (MBCT), it used the six indices of Ingram (2000). These six indices include magnitude of change, universality of change, generality of change, generality of change, stability, and acceptability. Results: Finding showed mindfulness– based cognitive therapy is both clinically and statistically (p<0. 01) significant efficient on the reduction of people with symptoms of complicated grief Conclusion: Mindfulness– based cognitive therapy has appropriate efficacy in the symptom reduction of people suffering from complicated grief.