Respiratory function, assessed by pre- and postoperative spirometry, and overnight pulse oximetry recordings, was compared prospectively in patients undergoing infrarenal abdominal aortic aneurysm repair by endovascular or conventional surgery. Episodic hypoxaemia was common in both groups before operation and up to the fifth night after operation. The frequency and severity of hypoxaemia were greater in the conventional group (P < 0.05). FEV1 and FVC decreased significantly on the third and fifth days after operation in both groups (P < 0.05); decreases in FVC were greater in patients undergoing conventional surgery. On the fifth day after operation, FVC had recovered to 86% and 64% of preoperative values in the endovascular and conventional groups, respectively (P < 0.05). Duration of surgery was greater (P < 0.05) and duration of postoperative artificial ventilation significantly less (P < 0.05) after endovascular repair. Postoperative PCA morphine consumption and duration of use were significantly greater (P < 0.05) in patients undergoing conventional abdominal aortic aneurysm surgery.