The present study was conducted to further our understanding of the relationship between performance on neuropsychological tests and functional status after head injury and to provide information on the relative usefulness of neuropsychological tests as outcome measures in clinical trials of brain injury. We sought to select the fewest number of 19 neuropsychological tests administered to 110 patients that, in combination, were most closely related to outcome (as measured by the Glasgow Outcome Scale (GOS) and to the remaining neuropsychological measures. The relationship of memory and intellectual deficits to functional status was also considered. To address these questions, we analyzed 19 neuropsychological measures and GOS scores of 110 severely brain injured patients from the Traumatic Coma Data Bank. Of 19 neuropsychological measures compared with GOS at 3 and 6 months, four tests (Controlled Oral Word Association, Grooved Pegboard, Trailmaking Part B, and Rey-Osterrieth Complex Figure Delayed Recall) provided the closest relationship to GOS and to the remaining 15 tests. Similar analyses were performed on 30 moderately injured patients to test the generality of our findings across different levels of patient severity. The same four tests were found to be highly predictive of GOS. Grooved Pegboard, a test of fine motor coordination, accounted for 80% of the variation in GOS. Fifteen percent of 116 patients with severe brain injury could not complete a neuropsychological battery and 39% were excluded because of previous brain injury or known substance abuse.