The pedigree of a family where three of nine siblings had suffered from aneurysmal subarachnoid haemorrhage (SAH) was explored, by means of interviews and revisions of population and medical records. We thus found two nephews with previously ruptured intracranial aneurysms. Subsequently high resolution computerised tomography (CT) scans were performed in the remaining six siblings, one of which was shown to harbor an intracranial aneurysm. This individual was subjected to uncomplicated clipping of the aneurysm. Typing of human leukocyte antigen (HLA) was performed in 15 individuals of the pedigree. Three of the six HLA-antigens recently reported to occur in increased frequently in a series of (non-familial) patients with ruptured aneurysm were found, namely B7, DR2 and Cw2. Most noteable was the expression of the antigen B7 in five of the six individuals with aneurysm in the investigated family. At present HLA-typing is not a useful screening tool to identify individuals in the general population with an increased risk of developing intracranial aneurysms. The present study shows that HLA-typing could neither be used to predict the occurrence of intracranial aneurysms in the siblings in the investigated family. HLA-typing may provide further clues to our understanding of the etiology of intracranial aneurysms, especially concerning possible genetic factors. The authors thus would like to encourage HLA-typing in previously known and newly detected families with accumulation of intracranial aneurysms.