A study of coroner's necropsy statistics showed that subarachnoid and cerebral haemorrhage were important causes of sudden death in the community. There were more sudden deaths due to cerebral haemorrhage in women than in men but this was due to the increasing frequency of this condition with age and the sexes were equally affected if standardized mortality rates were calculated. Comparison with a study of hospital necropsy statistics showed that the latter was a selected group, elderly patients (predominantly women) being found less frequently. Deaths due to subarachnoid haemorrhage occurred as commonly in men as in women, but were rare over the age of 60 years. This fact probably accounted for the similar epidemiology of these fatal cases in the hospital and the community.
There was no significant seasonal variation in the death rate due to either cerebral or subarachnoid haemorrhage if surgically treated cases were excluded.
The mortality of both these conditions was highest at the onset and rapidly decreased. A secondary rise in mortality due to subarachnoid haemorrhage occurred between the sixth and eighth days after the onset in the hospital group. The length of survival before treatment is an important prognostic factor and must be known before the effect of treatment can be assessed.