Patients with multiple intradural aneurysms present unique clinical challenges, particularly when presenting with subarachnoid haemorrhage. This study was undertaken to retrospectively review the management of such patients treated at a single institution. Consecutive patients with multiple intradural aneurysms managed at our institution between 1993 and 1999 were studied. The 122 patients had a total of 305 aneurysms. In most patients presenting with subarachnoid haemorrhage, the aneurysm responsible for the bleed could be identified with a fair degree of certainty, as confirmed by subsequent surgical and autopsy findings. Irregularity of the aneurysm (false sac or polylobulation) was the most useful criterion for making this determination. Failure to recognize all aneurysms on the original angiogram remained an uncommon but clinically important problem. Posterior inferior cerebellar and anterior communicating artery aneurysm locations were disproportionately more likely, and para-ophthalmic less likely, to be responsible for the subarachnoid haemorrhage. There was a trend for patients with uncertainty regarding the site of bleeding to have all aneurysms treated, and for cure to be obtained in a shorter time. Surgical and endovascular complication rates and patient outcomes were not dissimilar from what one would expect for single aneurysm patients. During follow-up, we observed a haemorrhage rate from unruptured aneurysms of 1.1% per patient-year of observation, and a de novo aneurysm formation rate of 0.76% of patients per year. In conclusion, we feel that although patients with multiple intradural aneurysms have more complex management issues than those with single aneurysms, good outcomes can be achieved with appropriate use of endovascular and/or surgical therapy. The goal in the acute setting following subarachnoid haemorrhage is recognition of all aneurysms and urgent treatment of the one responsible for the haemorrhage. When there is uncertainty, more than one aneurysm may need to be treated. Decisions on subsequent treatment of remaining unruptured aneurysms must be individualized.