Depression is one of the most common psychological disorders, that is attened by psychologists. There are many treatment method for depression. According to research findings, family has important role in creating, maintaining and treating of depression syndrome, also research findings showed that Cognitive-Behavior Therapy (CBT) is effective in treatment of depression. Therefore, family therapy based on cognitive-behavioral approach, is suggested in treating depression.

The main aime of this study was to explore the effect of family therapy based on cognitive-behavioral approch as an effective treatment.

Method of the study was case study research. Data were obtained by clinical interview and psychological tests. In this study, a severly depressed subject (17 years old) was treated by using on CBT family therapy.

Almost all the subscale of MMPI and SCL-90 and other instruments showed significant decrease in psychological problems after therapy as compared with the obtained results before the therapy.

It can be concluded that some probable reasons for decreasing the depression of the client included solving conflicts and interpersonal problems by means of training certain skills such as problem solving, developing relationship with others, effective coping, assertiveness and positive thinking were effective. Consistency and inconsistency of the results was discussed.