Background: Health education is an essential component of nursing care aimed at promoting, maintaining, and restoring health, as well as enhancing patient coping to the residual effect of illness. Many factors might affect nurses' practice of their role as educators. Aim: to assess nurses' knowledge and health education ability in certain chronic diseases, identify the factors affecting nurses' role as educators, and assess related patient. Subjects and methods: this cross-sectional study was conducted at the critical care and medical departments in Zagazig university hospitals. The subjects consisted of 46 nurses and 46 patients admitted to the mentioned setting. Tools for data collection included a self-administered questionnaire to assess nurses' knowledge and ability to provide a health education message in simulated situations, and opinions about barriers to health education, and a structured interview form for patients. Results: none of the nurses had satisfactory knowledge regarding health education, and only 23.9% had adequate health education ability. The most important barriers for nurses 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 condition. 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, and 19.6% attributed negative effect on their health condition to wrong health information. Conclusion and recommendations: 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 own illness. Therefore, there is a need for preparing staff nurses as teachers through continuing education.