Background: Clinical supervision (CS) is becoming standard practice for health professionals, and has been considered to be an important component of comprehensive clinical governance.  Also CS has been promoted as a key clinical governance component to ensure the provision of and accountability for the quality of care provided to patient and to minimize the risk of adverse outcome for patient. Aim: to investigate the effect of an educational program about clinical supervision for first line nurse managers on quality of their clinical supervision. Setting: The study was carried out at Minia University Hospital; Gynecology, Obstetric and Pediatric University Hospitals. Subject: A convience sample of first-line nurse managers' (no.= 50) and staff nurses (no.= 300) were included in the study. Tools: Three tools were used in this study; Clinical supervision knowledge questionnaire, Clinical Supervisor self-assessment questionnaire and Manchester Clinical Supervision Scale (MCSS). Results: The total knowledge score and levels of CS, and its subscales among first line nurse managers were low before the program implementation; after the program implementation they had high scores with statistically significant differences; also the staff nurses perception about first line managers were low before program and became higher after the implementation. Conclusions:  statistically significant increase in the knowledge test scores have been found after program implementation and during the different periods of testing. Recommendations: Clinical supervision program should be periodically conducted for all head nurses, integrate the clinical supervision in the philosophy of the hospital, and first line managers should periodically have nursing group meeting to verbalized, vitalize and support peer and social interaction develop supportive working conditions and relationship that encourage trust, empathy and mutual regard; put and identify the work policies and routine in place and allow supervisees to know their limitations.