Childhood injuries constitute a major public health problem worldwide. First aid is an effective life-preservation tool at work, school, home, and in public locations. In this study, the effectiveness of a first-aid program delivered by undergraduate nursing students to preparatory school children was examined. This quasi-experimental study was carried out on 100 school children in governmental preparatory schools in Egypt. The researchers designed a program for first-aid training, and this was implemented by trained nursing students. The evaluation involved immediate post-test and follow-up assessment after two months. The results showed generally low levels of satisfactory knowledge and inadequate situational practice among the school students before the intervention. Statistically-significant improvements were shown at the post- and follow-up tests. Multivariate regression analysis identified the intervention and the type of school as the independent predictors of the change in students' knowledge score, while the intervention and the knowledge score were the predictors of the practice score. The study concluded that a first-aid training program delivered by nursing students to preparatory school children is effective in improving their knowledge and practice.