Magnetic resonance (MR) imaging is a sensitive means of detecting haemorrhagic and nonhaemorrhagic forms of brain injury. This study correlates the neurobehavioural (NB) deficits in 49 adult patients with lesions detected by MR imaging. MR imaging was performed 2-19 days following trauma, analyzed for the injury type and graded for severity. A battery of NB tests was performed prior to hospital discharge or at the time of initial follow-up visit (31 patients). 15 patients were so severely impaired that testing could not be done and 3 died prior to discharge. The NB test scores were grouped into 3 levels of impairment. The overall NB scores were compared with MR lesion severity ratings and a positive correlation found (r = 0.47). In addition, lesion severity, type and location resulted in specific NB deficits. We conclude that the lesion location and severity can be accurately identified by acute phase MR are associated with specific types of neurobehavioural deficits in a high percentage of testable patients.