Specialist surgical registrars perform surgery as a requirement of their training, but the effect of the surgeon's level of training on outcome in intracranial aneurysm surgery is not known. This study addresses this question. A cohort of 278 consecutive patients who underwent a craniotomy to clip a recently ruptured intracranial aneurysm between January 1995 and December 1999 was assessed. Patients were divided into three groups according to whether the operating surgeon was a registrar, a senior registrar or a consultant. The frequency of a good outcome (defined as a Glasgow outcome score of 5) was compared in the three groups. Registrars operated on 91 patients (33%), senior registrars on 60 (21%) and consultants on 127 (46%). Between the three groups there was no statistically significant difference in patient age, male: female ratio, the timing of surgery after the haemorrhage, or the proportion of patients requiring preoperative ventriculostomy or with angiographic vasospasm, but more patients operated on by consultants had favourable admission World Federation of Neurological Surgeons grades. About two-thirds of patients achieved a Glasgow outcome score of 5 at 6 months, and there were no statistically significant differences in outcome between the three groups at discharge, at 6 months and at 1 year. Intracranial aneurysm surgery by trainees and consultants was not associated with differences in patient outcome in a cohort of patients treated at a University teaching hospital.