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.