Abstract. Objective: To describe the incidence and patient characteristics of traumatic brain injuries (TBIs) treated in U.S. emergency departments (EDs). Methods: A secondary analysis was performed on data from the National Hospital Ambulatory Medical Care Survey administered from 1992 to 1994. An ED visit was determined to represent a case of TBI if the case record contained ICD-9-CM codes of 800.0-801.9, 803.0-804.9, or 850.0-854.1. Results: The average annual estimate of new TBI treated in U.S. EDs was 1,144,807, equaling 444 per 100,000 persons (95% CI = 390 to 498), which represents approximately 3,136 new cases of TBI per day and accounts for 1.3% of all ED visits. Males were 1.6 times as likely as females to suffer TBI until the age of 65 years, when the female rate exceeded the male. The rate for blacks was 35% higher than that for whites. The highest overall incidence rate of TBI occurred in the less-than-5-year age group (1,091 per 100,000), closely followed by the more-than-85-year age group (1,026 per 100,000). Falls represented the most common mechanism of TBI injury, followed by motor vehicle-related trauma. Conclusions: This study underscores the ongoing need for effective surveillance of all types of TBI and evaluation of prevention strategies targeting high-risk individuals. It serves as a clinically grounded and ED-based corroboration of prior survey research, providing a basis for comparison of incidence rates over time and a tool with which to measure the efficacy of future interventions.