ObjectiveTo determine the operative morbidity and mortality of carotid endarterectomy in South Australia.DesignThis was a prospective study on consecutive patients already selected independently by their treating clinicians for carotid endarterectomy. Patients were assessed before and after the operation by independent neurologists.Setting and participantsThe study involved all patients undergoing carotid endarterectomy in South Australia in public and private hospitals over the 20‐months period of the study. All vascular surgeons agreed to participate.InterventionTwo hundred and thirty‐nine carotid endarterectomies were performed on 223 patients, always as primary procedures.Main outcome measuresPatient characteristics, angiographic findings and indications for surgery were documented before the operation by neurologists who then carried out postoperative assessments and determined neurological status at discharge. Follow‐up at six and twelve months was by letter and telephone enquiry to general practitioners or direct to patients.ResultsThe perioperative death and stroke rate was 6.3% including one stroke after angiography and before endarterectomy. Fourteen patients (5.9%) had strokes after the operation and three died as a result (1.3%). Three patients had reversible ischaemic neurological deficits. In 58 asymptomatic patients, operative morbidity was 3.4%. However, in 42 patients who had had a stroke before the operation, there were seven who had operative complications (16.7%). Neurological complication rates for individual surgeons varied from 0 to 13.8%. In the subsequent 12 months, follow‐up of 214 patients revealed nine additional deaths (three known to be caused by stroke, four not caused by stroke and two of unknown cause) and six more cerebral infarctions (involVing both operated and unoperated sides), an annual mortality plus stroke morbidity rate of 4.2%‐5.1%.ConclusionsThe morbidity and mortality of carotid endarterectomy in South Australia is acceptable by world standards but is high in the subgroup with a preceding stroke. In this audit, carotid endarterectomy had an average risk at least equal to one year of untreated carotid artery disease and did not diminish the expected stroke and death incidence after one year.