Environmental school is the most setting for unintentional injury which lead to morbidity and mortality among children worldwide. The study aimed to evaluate effect of training program of some selected first aid measures on knowledge and practice among preparatory school children. A quasi experimental study was applied for this study. The present study was conducted at Al-Nasiriya Preparatory School in Zagazig city. Two tools were used; first a Structured Interview Questionnaire to collect data about studied children’s characteristics and their knowledge about first aid and the second tool was Reported Practice Checklist to evaluate studied children’s practice regarding first aid. The study results indicated that 87.3% of the studied children had unsatisfactory knowledge and 89.8% of them had unsatisfactory practice before implementation of training program. While 76.3% of the studied children had satisfactory knowledge and 78% of them had satisfactory practice after implementation of training program. It can be concluded that the training program had improved studied children’s knowledge and practice about first aid. Therefore, this study recommended that the use of innovative methods of health education in teaching first aid for other sectors as in secondary school students as well as in primary school students to promote children’s health. Key words: Training program- preparatory school children- first aid