Objective:To determine the outcome in patients with subarachnoid haemorrhage from a ruptured aneurysm, particularly in those in who,“ the diagnosis w.as delayed.Design:A two‐year retrospective study of medical records of patients admitted to Westmead Hospital between July 1988 and June 1989.Setting:A tertiary level teaching hospital.Patients:Ninety‐four patients treated for subarachnoid haemorrhage. In 15 cases the diagnosis was delayed.Main outcome measures:Death, disability, or functional recovery.Results:Overall, 40 (42.5%) patients died, 14 (15%) were disabled, and 40 made a functional recovery. Of the 62 patients who were treated surgically 38 (61%) made a functional recovery compared with two of the 32 (6%) who were not. Of the 15 in whom the diagnosis was delayed seven (47%) made a functional recovery. Confirmation of the diagnosis was delayed in four of the latter group because a cranial computed tomography scan showed no abnormalities.Conclusions:Earlier diagnosis, allowing early definitive surgical treatment, may improve the outcome in aneurysmal subarachnoid haemorrhage; The results ofa computed tomography scan are diagnostic only if they are positive ‐ a negative result must be interpreted in conjunction with the clinical picture.