Psychosocial and behavioral variables play an important role in both the development and treatment of obesity. Therefore, in the process of qualifying the patient for bariatric surgery, it is necessary to professionally evaluate his/her psychological state. Such evaluation is very helpful in the identification of factors potentially disturbing the effectiveness of the treatment. Clinical interviews with a group of 80 patients were conducted by a psychologist in the pre- and post-surgical period. The qualitative analysis of the interviews led to the identification of the major elements which should become the object of psychological evaluation in the process of qualifying patients for bariatric surgery. Conducting a clinical interview comprising these elements allows one to evaluate their potential influence on the process of surgical treatment of obesity and to provide optimal psychological support for the patient before and after the surgery.