CDC, in collaboration with the Consumer Product Safety Commission (CPSC), expanded CPSC's National Electronic Injury Surveillance System (NEISS) in July 2000 to include all types and external causes of nonfatal injuries treated in U.S. hospital emergency departments (EDs). This ongoing surveillance system, called NEISS All Injury Program (NEISS-AIP), can be used to calculate national, annualized, weighted estimates for nonfatal injuries treated in U.S. hospital EDs. This report summarizes NEISS-AIP data, which indicate that approximately 1.6 million persons were treated in U.S. EDs during 2000 for nonfatal physical (i.e., nonsexual) assault-related injuries. Such injuries occurred disproportionately among males, adolescents, and young adults, particularly among black males; most of these injuries were contusions or lacerations, few of which resulted in hospital admission. NEISS-AIP data can increase understanding of physical assault-related injuries and serve as a basis for monitoring trends, facilitating additional research, and evaluating intervention approaches.