Neuropsychological outcome and recovery of a group of 91 patients with moderate-to-severe head injuries were prospectively investigated over a 2 year period, with evaluations at acute hospital discharge at 6 months and 2 years post-injury. A group of 39 trauma patients with injuries to parts of the body other than the head were used as controls. The head injured group performed significantly worse than the control group at baseline, 6 months and 2 years post-injury. Significant improvement was found during the first 6 months, but also between 6 months and 2 years post-injury. Trauma controls also performed significantly better at 6 months post-injury compared to baseline. Differential practice effects between groups cause difficulties in determining recovery. Within the head injured group, three distinct recovery groups were identified varying as a function of coma-length and coma-duration. The first group is comparable with the trauma controls. The other two groups demonstrate significant neuropsychological impairments at baseline, with one group showing a marked improvement over the 2 year period, and the other group showing only small improvement over this time period.