The current study aims at verifying the effectiveness of a cognitive behavioral therapyprogram for the development of environmental psychological compatibility in a sample of children with cancer, the study sample consisted of (40) children divided as (20) children for the experimental group and(20) children for the control group,Based on a cognitive behavioral therapyprogram. Several tools were used in the program to collect data from the research community. The use of the psycho-environmental compatibility scale is considered as a mean to serve the program's goal by applying it to children before and after the application of the program and also as a tracking measure, the study provided the basic data needed especially the type of disease, the duration of treatment and the type of treatment used. The study depended on dealing with children who experienced chemotherapy as a basic condition in the study. The study has ended to a result of development of the psycho-environmental compatibility in children with cancer for the experimental group that the researcher applied the program to them, while the children of the control group who did not experienced the program did not achieve any significant improvement on the scale of the psycho-environmental compatibility. and the reasons whythe control group did not achieve any significant improvement are the bad psychological state they are experienced because of their exposure to chemotherapy and their feelings of anxiety, fear and depression due to the pain and the various side effects either for the disease itself or the treatment, which affects the compatibility with themselves or with the surrounding environment, Family, friends, colleagues, teachers and neighbors, and the acceptance of the physical environment around them, which the study has succeeded in improving significantly using the cognitive behavioral therapyprogram, and this is confirmed by the results of the study.