Objectives: To investigate factors associated with a prolonged hospital stay after elective open surgical repair of abdominal aortic aneurysm. Patients and methods: We have investigated prospectively base-line risk factors associated with an increased length of postoperative hospital stay in 474 of the patients undergoing surgery as part of the U.K. Small Aneurysm Trial. Results: The median length of hospital stay was 11 days (interquartile range 9-14 days). Age (within the range 60-76 years), sex, body mass index, aneurysm diameter, graft type (tube or bifurcated), hospital (university or other), ECG characteristics, angina (from Rose questionnaire) and/or previous myocardial infarction were not associated with length of hospital stay. Quality of life also was assessed before surgery using the Medical Outcomes Study SF20. Psychosocial aspects including level of social functioning, role functioning, mental health, health perceptions and pain were not associated with length of postoperative stay. The level of preoperative physical functioning was associated inversely with length of hospital stay, p = 0.004. Patients' length of hospital stay also was inversely associated with preoperative lung function: FEV1, p = 0.011 and FVC, p = 0.006. In contrast, smoking habit was of only borderline significance, p = 0.09. Conclusion: Conditional logistic regression analysis identified only preoperative lung function (FEV1 and FVC) and physical functioning, three intrinsically linked factors, as predictors of length of hospital stay after elective repair of an abdominal aortic aneurysm.