Three women aged 55, 47 and 40 years with polycystic kidney disease had several relatives with cystic kidneys, some of whom had died or been crippled after (presumably) a subarachnoid haemorrhage. Two of these patients had a haemorrhage from an aneurysm of a cerebral artery; after clipping of the vessel they recovered without sequelae. The third patient had magnetic resonance (MR) angiography performed, which revealed no aneurysm. The prevalence of intracranial, saccular aneurysms in patients with autosomal dominant polycystic kidney disease (ADPKD) is about 10%. ADPKD patients with questions about the risk of a subarachnoid haemorrhage should be informed about the need of blood pressure control and the possibility of screening by MR angiography. Diagnosed aneurysms can be treated neurosurgically or endovascularly. Since aneurysms develop in the course of life, screening as a rule is only necessary from the age of 20 years, and its repetition every 5 years should be considered.