Background: Immunization is one of the most cost-effective interventions for the child health promotion. It is a safe and effective method of preventing many series of major illnesses. Nurses need to be confident, knowledgeable and up to date.  A high level of knowledge and practice of immunization in healthcare workers is an important element in achieving and maintaining high vaccine uptake. Aim: Assessing the Effect of Educational program for nurses on their knowledge regarding obligatory vaccination for children. Research design: This study used pre/post Quasi- experimental research design. Sample: All nurses who are working in the (7) health office and centers at Minia city and responsible for vaccination of children the total numbers of nurses were 39 nurses. Setting: The selected vaccination office and centers represented all geographic areas of Minia City as this study was conducted in (7) places. Tools for Data Collection: One of tool was used in this study, structured interview questionnaire in Arabic language. It was composed of the following parts: Part 1: demographic data about nurses including nurses' age, qualification, years of experience and previous training courses about vaccination. Part 2: knowledge assessment questionnaires to assess the nurses' knowledge about vaccination. Results: The finding of the current study revealed that there were statistically significant differences between nurses' knowledge at pre and post- program. Conclusion: The study concluded that the health education program was effective in improving nurses' knowledge in post program than before about general information, infection control, BCG, DPT vaccine and the health education which must be given for parents. Recommendation: The study recommended that the provision of continuing education programs on regular basis is suggested in order to refresh and update nurses' knowledge related to vaccination and infection control measures.