Introduction: Patient education is one of the most important roles of the nurse. It is an effective tool for health promotion. It gains more importance in chronic diseases, with long duration of illness and treatment. Health education is effective if it succeeds to change a person' health -related behaviors. Cases with chronic illnesses and short hospital stays require more attention for giving additional information to both patients and their families to assist them in improving their daily life. The social change approach is aimed at changing the environment to facilitate the chance of lifestyle modification, and increase of health aspects. The aim of this study: To assess nurses' knowledge and health education ability in certain chronic diseases, identify the factors affecting nurses' role as educators, and assess related patient. Research design: Cross-sectional research design was used. Setting: The critical care and medical departments in Zagazig University Hospitals. Subjects: The present study consisted of 46 nurses and 46 patients. Tools of data collection: Tools included a self-administrated questionnaire to assess nurses' knowledge and ability to provide a health education message in simulated situation, and opinions about barriers to health education, and a structured interview from the patients. Results: The study indicated that, none of the nurses had satisfactory knowledge regarding health education, and only 23.9% had adequate health education ability. The most important barriers for nurse's role as educators were lack of trust, lack of continuity of care, and lack of suitable setting for health education. Only (39.1%) of the patients had total satisfactory knowledge regarding their education. The highest percentage of satisfactory knowledge was regarding dietary regimen (52.2%), while the lowest was about treatment (19.6%). Also, the study revealed that (67.7%) of patient subjects had some complications; (8.7%) of them thought these complications were due to medication errors. Recommendation: Studied nurses have unsatisfactory knowledge and inadequate practice of their educator role. This deficient health education ability has a negative reflection on patient related knowledge about illness. There for, there is a need for preparing staff nurses as teachers through continuing education. Moreover, the curriculum of nursing students has to address teaching and learning principles include in more breadth and depth. Furthermore, formal preparation of student nurses as educators has to be a part of undergraduate curricula in nursing schools' program.