The charts of 370 children under the age of two years who presented to a pediatric emergency department between September 1988 and August 1989 were reviewed. Twenty-seven patients (7% of the total) had injuries associated with child safety seat (CSS) misuse. Thirteen were infants and toddlers injured as motor vehicle occupants when improperly restrained--CSS harness not properly connected (8), use of an improper device (3), and CSS not anchored to the car seat (2). Fourteen were infants under one year of age who were injured falling in their CSS. Injuries included minor head trauma (17), linear skull fracture (5), concussion (1), femoral fracture (1), depressed skull fracture with epidural hematoma (1), cervical vertebral fracture (1), and intraventricular hemorrhage (1). Nine patients were hospitalized. Injuries associated with CSS misuse may be more common than previously recognized and can result in significant injury. Educational efforts should focus on correct usage.