Accidents are the first cause of mortality and morbidity in children and adolescents of both sexes as from their first month of life. Also they are the first cause of hospitalization and thus have an important economical impact. The knowledge of the mechanisms of injury can neither be transposed from a place to another nor be extrapolated with time. For this reason we developed in 1989 a prospective data base for injuries of children and adolescents from 0 to 16 years of age occurring in our state (canton de Vaud, Switzerland). From Jan 1st, 1990 to Dec 31st, 1999, we recorded more than 28,000 cases. Infants and young children are involved in domestic injuries, accidents on playgrounds and in traffic accidents being pedestrians or passengers. We analyze the circumstances of accidents and point out their prevention programs and their efficiency. We try to demonstrate why children injuries are not fatalities but depend on mechanisms which can be predicted inarticular by an adequate information.