Objective: Organized athletics provides an excellent laboratory for studying mild traumatic brain injury (concussion). Over the past decade, numerous studies have examined the use of neuropsychological assessment techniques to monitor acute recovery following sports-related concussion. Recent application of computer-based neuropsychological screening tools has played an important role in this area of research. In addition to evaluating the traditional domain of memory, computer based approaches allow for more precise measurement of cognitive speed, recorded at higher levels of accuracy than possible through traditional means (e.g. stopwatch). The ImPACT computer-based test battery was designed to capture the interplay between cognitive speed and memory (cognitive efficiency). Within this context, cognitive efficiency incorporates both accuracy and speed. This is important because concussed athletes may sacrifice either speed or accuracy when faced with a difficult task. Participants and Methods: This study evaluated the interplay between speed and accuracy on the Symbol Match subtest of ImPACT. Symbol Match is similar to Symbol Digit Modalities but measures response time in milliseconds. This task also includes the number of items accurately recalled. For this study, a Cognitive Efficiency Index score was calculated for a sample of 252 concussed athletes. This clinical group was compared to an age-matched control group (N=85). Results: Concussed athletes performed significantly more poorly than did non-injured athletes on the CEI (p<.02). Conclusions: The CEI provides useful information regarding the trade- off between speed and accuracy. This measure may provide a useful metric of the evaluation of recovery post-injury.