Background: Covid-19 has become a global health threat that affected public health. Aim: Evaluate the effect of preventive program about COVID 19 for nurses. Design: A quasi experimental research design. Setting: This study was conducted at 25% of the total Health Administrations in Qualyobia Governorate. Sample: All nurses in the selected Health Administrations (n= 130). Tools: I): A structured interviewing questionnaire to assess: a): Socio-demographic characteristics of the studied nurses.  b): Health status of the studied nurses during last six months. c): Nurses' knowledge about COVID 19. II): Likert scale­ to assess nurses' attitude toward prevention of COVID 19. III): An observational checklist to observe a): Nurses' practices regarding prevention of COVID 19. b): The environmental safety of MCH centers. Results: 50.8% of the studied nurses had good total knowledge score about COVID 19 and its prevention at pre-program implementation then increased to 93.8% at post program implementation, 30.8% of the studied nurses had positive total attitude score related COVID 19 and its prevention at pre-program implementation compared to 83.8% at post program implementation, 26.2% of the studied nurses had satisfactory total practices level toward prevention of COVID 19 at pre-program implementation then increased to 88.5% at post program implementation. Conclusion: Preventive program about COVID 19 succeeded to improve knowledge, attitude and practices of nurses regarding Covid-19. Recommendations: Periodic health educational programs for nurses should be made to improve nurses' knowledge, attitude and practices regarding prevention of COVID 19.