Porcine livers were preserved for 72 h using continuous hypothermic perfusion with UW solution and fluorocarbon emulsion (FC-43). They were then recirculated with human blood for 2 h at 37 degrees C for the evaluation of their viability. During hypothermic perfusion and recirculation, the main metabolites of the perfusate and adenine nucleotide concentrations were measured in order to examine the energy metabolism of the livers. This study revealed that hypothermically perfused livers, which mainly utilize endogenous fatty acids as an energy substrate during this time were adequately preserved for 72 h. In terms of energy metabolism, it is suggested that when using the method of continuous hypothermic perfusion with UW solution and FC-43, the administration of adequate amounts of certain fatty acids might prolong the preservation period.