The purpose of this study was to examine the effects of systemic perfusion temperature on the clinical outcome after aortic valve surgery. In this study, we examined 323 patients who underwent aortic valve surgery between January 1994 and April 1996. Forty-six patients were perfused in moderate hypothermia (28 degrees C) and 277 patients in normothermia. Age and sex distribution of the patients were similar. There were no statistically significant differences between the groups regarding neurological, renal or cardiac complications. Patients in hypothermia required less catecholamine at the end of the operation (p = 0.00001), but there was no significant difference in the length of the stay in the intensive care unit between the groups. Cardiopulmonary bypass temperature did not influence early outcome after aortic valve surgery.