Cancer is the leading cause of death in economically developed countries and the second leading cause of death in developing countries. About half of all cancer patients are treated with radiation therapy, because the radiation destroys the cancer cells' ability to reproduce. Quality of life has become an important gauge for evaluating healthcare outcomes. Provider's cares ''for radiation therapy patients and its treatment'' have been front runners in the evaluation of quality of life. Aim: to assess the effect of a health educational program on quality of life of cancer patients receiving radiotherapy. Study hypothesis is that: By completion of the program, quality of life total score among the study group who participated in the program will be higher than that of the control group. A quasi experimental design was conducted at the Outpatient Clinic of Radiotherapy in Ain Shams University Hospital. Sixty adult patients equally distributed as 30 study and30 control groups. The tools of data collection were 1) A patients' assessment sheet constructed by the researcher, 2) An interviewing questionnaire sheet, 3) Quality of life scale developed to assess the impact of cancer on the quality of life of cancer patients, and Proposed management program. Results: showed slightly improvement in patient's quality of life after one month from giving the educational program, while after three months there were general improvements in all dimensions of quality of life; physical, psychological, social, and spiritual status. Conclusion : all patients under radiotherapy need to improve knowledge about radiotherapy before starting the course of treatment for overcoming the side effects. Recommended : there is a need to plan and conduct an in service training program to the radiotherapy nursing staff about their role in controlling side effects of radiotherapy.