Based on a strict definition of whiplash injury, a sample of 117 non-selected patients was examined 7.2 +/- 4.2 days and at 3, 6 and 12 months after trauma. Initially all patients underwent a neurological examination, cognitive and psychosocial factor assessment and cervical spine x-rays. 56%, 70% and 76% of patients had completely recovered at 3, 6 and 12 months respectively. The results indicated that impairment of patients' well-being and cognitive ability was closely associated with somatic symptoms. No major impairment of attentional functioning was found, but some change in cognitive equilibrium was observed which may be related to the type of medication utilized. Delayed recovery at 12 months could be predicted by the following initial variables: higher age, intensity of initial neck pain and headache, symptoms of radicular irritation, sleep disturbances, pretraumatic headache, history of head trauma, nervousness score and--significantly inversely proportional--initial concentration problems and neuroticism score. These results suggest that a more severe neck injury may in particular account for delayed recovery from whiplash.