The article describes the case of a 21-year-old patient hospitalized because of the diagnosis of acute myeloid leukemia. The purpose of this paper is the presentation of mindfulness training as a method supporting the process of adaptation to the disease and treatment. The results of the psychological analysis indicators showed that at the commencement of psychotherapy patient was in the initial stage of the process of adaptation to the disease and treatment. The ways he coped with the desease exacerbated the negative side effects of treatment. If established, they could lead to abnormal course of adaptation and the emergence of dysfunctional behavior. Therefore it was decided to apply psychotherapy. Training has helped in changing cognitive and emotional experience of the disease and was, in the subjective perception of the patient, a beneficial way to change the regulation of emotion in the healing process.