Immediate preoperative phlebotomy with autologous blood donation for aortic replacement. The preferential use of autologous blood provided by phlebotomy can reduce the need for homologous blood transfusion in patients undergoing extensive elective operations. This blood is usually provided either by intraoperative isovolemic hemodilution or phlebotomy one to two weeks preoperatively. To minimize the intraoperative time delay or preoperative period between phlebotomy and operation required in these patients, we performed preoperative isovolemic hemodilution in 69 patients one to two days prior to elective aortic replacement for infrarenal aneurysmal disease. Patients underwent phlebotomy a mean of 0.57 +/- 0.01 liter of whole blood; volume was replaced with lactated Ringer's solution. Hematocrit levels decreased from a mean value of 42.9 +/- 0.4 per cent to 33.7 +/- 0.3 per cent. Mean intraoperative blood loss was 1.2 +/- 0.05 liters. Hemodynamic parameters (blood pressure, cardiac output, pulmonary capillary wedge pressure, central venous pressure, oxygen delivery and systemic vascular resistance) remained stable throughout the perioperative and intraoperative time periods. In addition, we evaluated the technical modification of exclusion aneurysmorrhaphy (n = 50) versus open aneurysmorraphy (n = 19) on reduction of intraoperative homologous blood transfusion in these patients. Seventy-two per cent (36 of 50) of patients whose aneurysms were excluded received no homologous blood intraoperatively. Blood loss was decreased in the excluded versus open aneurysmorraphy group, 920 +/- 90 milliliters versus 2,030 +/- 250 milliliters, as were homologous blood transfusion requirements, 175 +/- 35 milliliters versus 570 +/- 119 milliliters. Two patients died (2.9 per cent mortality rate), and there was no increase in morbidity. Surgical treatment of large aortic aneurysms is frequently performed on an urgent basis; thus, provision of autologous blood for this operation in a short period of time may be beneficial. Isovolemic hemodilution performed during the immediate preoperative period can reduce homologous blood requirements and be safely performed without adverse effects on mortality, morbidity and myocardial performance. Exclusion aneurysmorrhaphy may further reduce dependence on homologous blood. 