The population analysed consisted of 268 out of 819 patients of a European nimodipine multicentre trial on severe head injury, whose first CT scan after injury showed signs of subarachnoid bleeding. The study demonstrated the importance of traumatic subarachnoid haemorrhage (tSAH) per se as a prognostic factor. The outcome of patients with tSAH is significantly worse than that of patients whose first CT does not show subarachnoid blood (noSAH). The outcome was unfavourable (dead, persistent vegetative state, severe disability) in 60% of tSAH patients compared to 30% of noSAH patients (p < 0.001). The difference in mortality was 42% vs. 14% (p < 0.001). The six month follow-up of tSAH patients complying with the study protocol and treated with intravenous nimodipine, 2 mg per hour for 7 days, showed a statistically significant reduction of unfavourable outcome from 66% to 51% (p < 0.05), compared to placebo treated patients.