Eleven patients belonging to two generations of a Dutch family with cerebral and cerebellar haemorrhage, haemorrhagic infarction and infarction are described. Their ages varied from 44 to 58 years. The principal clinical characteristics was recurring cerebral haemorrhages, sometimes preceded by a history of migrainous headaches or mental changes. In 4 of the 6 autopsied cases, old and new multiple cerebral haemorrhagic infarcts and infarcts were found, in one case a single cerebral haemorrhage and in another a cerebellar haemorrhage. In 5 cases this resulted in secondary subarachnoid haemorrhage. In one case the infarcts were only slightly haemorrhagic and did not result in subarachnoid haemorrhage. This patient presented as dementia. Microscopically, in these 6 cases and in one biopsy specimen hyaline thickening of the walls of cortical arterioles was found. The arteries of the arachnoid showed marked tortuosity, concentric proliferation, and focal hyalinization of the walls. Amyloid was found in the hyalinized vessels in 5 cases, but not outside the central nervous system. We believe that we are dealing with an inherited disorder with an autosomal dominated mode of inheritance, in which microangiopathy leads to cerebral haemorrhage and (haemorrhagic) infarction. It seems likely that amyloidosis underlies the angiopathy, and that this family suffers from a condition similar to the one described by Gudmundsson in 1972.