Summary ― The aim of this study was to develop a method for perfusing isolated trout livers that would make it possible to study hepatic metabolism in the whole organ. Rainbow trout (Oncorhynchus mykiss Walbaum) subjected to different fasting periods of 24, 48 or 96 h were used in all the experiments. A non-recirculating system was applied at a flow rate of 0.2 mL/min. The perfusion medium was a specific saline solution for salmonids oxygenated by a multibulb glass oxygenator. Viability assays included the measurement of oxygen consumption, lactate dehydrogenase activity and liver metabolic capacity. In addition, a histological study was carried out. Our results showed that the metabolic capacity of the liver survived throughout the perfusion process and that the functioning of this organ changed depending on the length of the fasting period to which the animal had been submitted. The method described here was shown to be suitable for studying the