BACKGROUND: There are limited data on the epidemiology of serious injuries due to physical abuse of children. METHODS: We used the 2006 Kids' Inpatient Database to estimate the incidence of hospitalizations due to serious physical abuse among children <18 years of age. Abuse was defined by using International Classification of Diseases, Ninth Revision, Clinical Modification codes for injuries (800-959) and for physical abuse (995.50, 995.54, 995.55, or 995.59), selected assault codes (E960-966, 968), or child battering (E967). We examined demographic characteristics, mean costs, and length of stay in 3 groups of hospitalized children: abusive injuries, nonabusive injuries, and all other reasons for hospitalization. Incidence was calculated using the weighted number of cases of physical abuse and the number of children at risk based on 2006 intercensal data. RESULTS: The weighted number of cases due to abuse was 4569; the incidence was 6.2 (95% confidence interval [CI]: 5.5-6.9) per 100 000 children <18 years of age. The incidence was highest in children <1 year of age (58.2 per 100 000; 95% CI: 51.0-65.3) and even higher in infants covered by Medicaid (133.1 per 100 000; 95% CI: 115.2-151.0 [or 1 in 752 infants]). Overall, there were 300 children who died in the hospital due to physical abuse. CONCLUSIONS: This is the first study to provide national US data on the occurrence of serious injuries due to physical abuse in hospitalized children. Data from the 2006 Kids' Inpatient Database on hospitalizations due to serious physical abuse can be used to track trends over time and the effects of prevention programs on serious physical abuse. Copyright © 2012 by the American Academy of Pediatrics.