To determine the impact of different flush and reperfusion techniques on postreperfusion syndrome (PRS) and postoperative graft function, 100 transplants were randomly assigned into four groups as follows: group 1 (n=31), portal vein flush, no vena caval venting; group 2 (n=21), hepatic arterial flush, no vena caval venting; group 3 (n=29), portal vein flush with vena caval venting; and group 4 (n=19), hepatic artery flush with vena caval venting. Donor and recipient characteristics were similar. Extensive intraoperative and postoperative monitoring was performed and measurements were documented immediately before reperfusion and at 1, 5, 15, and 30 min after reperfusion. PRS was defined by three criteria: mean arterial pressure (MAP) <60 mmHg at 1 min after reperfusion, MAP <60 mmHg at 5 min after reperfusion, and a decrease of 30% or more for the MAP percent area under the curve during the initial 5 min after reperfusion (%AUC). Using these definitions, the overall incidence of PRS was 21%, 8%, and 43%, respectively. Group 1 was the most hemodynamically stable; the incidence of PRS in group 1 was 2/31 (7%) at 1 min and 8/31 (25%) using %AUC criteria compared with 7/21 (33%) at 1 min and 12/21 (57%) using %AUC criteria for group 2 (P<0.05). The patients in groups 3 and 4 (vena caval venting) demonstrated smaller percentage increases in serum potassium levels (as determined by %AUC; 4.3+/-6.8 and 0.3+/-5.4, vs. 15.1+/-8.1 for group 1 and 22.9+/-8.2 for group 2). The difference between group 4 and group 2 was statistically significant (P<0.05). The increases in serum potassium did not translate into increased cardiac or hemodynamic instability. Combining all data obtained over the first 30 min after reperfusion, there was no statistically significant difference in hemodynamic or biochemical changes noted among the four groups. Postoperative liver function was similar among the four groups. We conclude that portal vein flush without vena caval venting provided a lower incidence of PRS than any other technique. Vena caval venting decreased the release of potassium into the circulation. Postoperative graft function was not significantly affected by flush and reperfusion techniques.