This study provides descriptions of the types of injuries sustained by a sample of children (0-14 years of age) who were using a vehicle seatbelt at the time of a motor vehicle accident and who were subsequently evaluated and treated in a hospital emergency room. Data were obtained from a hospital monitoring system established in nine emergency room facilities in a single county in California. The analysis indicates that in some cases injured seatbelted children were injured in circumstances in which the seatbelt could not have been protective, e.g., vehicle deformation into the child, flying glass, etc. The analysis of the remaining cases of seatbelted children suggests that there are significant variations in mechanisms of injury as well as injury patterns for different aged children. In many of the cases of injury observed in this sample, even though the child had been restrained in the adult seatbelt, the anatomic characteristics of the child prevented optional protection. The research provides further evidence for the necessity for utilizing specially designed restraints for children at least up to the age of 10 years.