Long-term preservation of the liver is needed to transform liver transplantation from an emergency operation to an elective procedure and therefore to improve the results of liver transplantation. We explored the possibility of extending the cold ischemia time of the rat liver by using a preservation temperature below 0 degrees C together with the addition of a cryoprotective agent (2,3-butanediol) at a low concentration in the preservation solution. Rat livers were preserved for 72 h either with UW solution at +4 degrees C (group 1) or with a UW solution, to which 2,3-butanediol at 8% (at +4 degrees C (group 2) or at -4 degrees C (group 3, experimental group)) was added. Following the preservation process, the viability of the livers was assessed using the isolated perfused liver model. Enzymatic release, bile production, and portal venous flow were not significantly different between group 1 and group 3. In the two groups in which preservation included 2,3-butanediol, the enzymatic release was significantly greater when the preservation temperature was +4 degrees C. We conclude that, using this method, preservation of the rat liver below 0 degrees C seems feasible. However, despite its low concentration, some toxicity of 2, 3-butanediol was suspected. This would counterbalance the benefit resulting from the temperature-related decrease of the enzymatic activities involved in cold ischemia damage. The potential advantages of this method need to be confirmed by assessing liver viability using a liver transplantation model.