The objective of this study was to assess the effect of insurance status and demographic characteristics on ED disposition among patients with traumatic brain injury (TBI). Statewide hospital discharge and ED datasets in South Carolina, 1996-2001, were analyzed by primary or secondary diagnosis of TBI in a multivariable logistic regression model. Of 70,671 unduplicated patients with TBI evaluated in the ED, 76% were treated and released; 26% had no insurance. The strongest predictors of hospital admission were TBI severity and preexisting health conditions. However, the uninsured and black females were less likely to be hospitalized after adjusting for demographic, clinical, and hospital characteristics (odds ratio [OR], 0.52; 95% confidence interval [CI], 0.48-0.55 and OR, 0.79; CI, 0.72-0.87, respectively). Although this study does not infer causality, insurance status, race, and gender were significant predictors of hospital admission. These results suggest that inpatient resources are not equitably used.