We have analysed eleven cases of intracranial haemorrhage occurring over the last 9 years in a population of 250 haemophiliacs. The purpose of this survey was to evaluate the prognostic possibilities available since the introduction of new diagnostic procedures and the progress in replacement therapy with anti-haemophilic factor. The sites of the haemorrhages and changes after treatment were visualized by CAT in 7 of the patients. Four patients died following dramatic evolution of their clinical conditions; two of them died before surgery, the others after having been operated on while in very deep coma. Two patients were successfully operated on for lesions occupying extracerebral spaces (one subdural and one extradural haematoma); replacement therapy avoided both recurrence and serious neurological defects. One patient with subarachnoid haemorrhage complicated by hydrocephalus was given an extrathecal shunt of cerebrospinal fluid. Four haemophiliacs had intracerebral haematomas: two of these needed surgery whilst the others recovered without serious neurological defects with replacement therapy only. These findings indicate that replacement therapy has considerably changed the prognosis of intracranial haemorrhage in haemophiliacs and that the CAT is a very helpful diagnostic procedure for evaluation of the acute stage and the follow-up.