A comparison of the effects of focal and diffuse axonal injury in mild-to-moderate traumatic brain injury (TBI). In a prospective longitudinal study of 138 consecutive patients suffering from TBI who were admitted to the Magdeburg University Hospital, 60 could be assessed neuropsychologically 8--31 days after trauma and 18--45 weeks later. GCS, CT-analysis, comprehensive neuropsychological assessment. The initial GCS-score was significantly correlated with outcome impairments of semantic fluency and memory in the Wechsler Similarities and in two clinical scales (Neurobehavioural Rating Scale, Frontal Lobe Score). The presence of CT-signs of DAI corresponded with deficits in tasks of response selection and suppression, the presence of focal contusions with results in the clinical scales, reaching significance for behavioural deficits with frontal contusions. Improvements between first and second assessments were pronounced in patients with signs of DAI. The data indicate that traumatic DAI results in mainly transient neuropsychological deficits. Focal frontal contusions result in more relevant deficits at outcome that affect behaviour and, thus, impair rehabilitation prognosis. It is concluded that even in clinically 'mild' TBI, prognosis and rehabilitation requirements should be established by early imaging and post-acute neuropsychological assessment.