Background: The aim was to investigate the effect of risk categorization on outcome from endoluminal aneurysm repair (ER) and to note changes in outcome with increasing experience. Methods:: Clinical and operative details of the first 70 patients undergoing ER (1995–1999) were analysed. American Society of Anesthesiologists (ASA) grade and POSSUM (Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity) score were determined. The cohort was divided arbitrarily into two groups: group 1 included the first 35 patients, and group 2 the second 35. Results:: Median age was 73 (55–93) years; 65 of the patients were men. The overall 30‐day mortality rate was seven of 70 (10 per cent). No deaths were directly attributable to the anaesthesia; four deaths were due to myocardial infarction. There was no difference in ASA grade or POSSUM score between the groups. Fourteen patients (20 per cent) were converted to open surgery, nine during the same period of anaesthesia as the ER. Group 1 (n = 35) Group 2 (n = 35) ASA III–IV2829Converted131Conversion mortality31Successful ER2234ER mortality12Overall mortality43 The odds ratio (OR) for conversion comparing groups 1 and 2 was significant, but the OR for total mortality and for mortality in those who had successful ER was not significant. Conclusion: ASA grading and POSSUM scoring has not changed with time. There was a learning curve, due largely to improvement in surgical technique. Four of the 14 patients undergoing conversion died; only one conversion occurred in the later experience. However, there was no statistically significant difference in total or ER mortality © 2001 British Journal of Surgery Society Ltd