The investigations were performed on 6 Friesian-Holstein heifers, weighing 410-504 kg, in which acid indigestion was induced by intraruminal administration of saccharose in a dose of 12 g/kg body weight. The animals were observed for 9 days after the treatment. Functional state of the liver was evaluated on the basis of bromosulphthalein clearance, total bilirubin level and aspartate amino-transferase (AspAT) activity in serum, concentration of blood glucose, total serum protein and protein fractions. Within the first 24 hours, all heifers developed acute symptoms of rumen acidosis which persisted for 3 days after saccharose administration. Afterwards, a phase of gradual spontaneous recovery was observed. In the course of rumen acidosis a reduction in bromosulphthalein clearance, an increase in bilirubin level and AspAT activity, a decrease and then an increase in glucose concentration and a reduction in albumin content and, as a consequence, in albumin/globulin ratio were found. The results indicate that experimental rumen acidosis produced disturbances in excretory and metabolic functions of the liver in the examined heifers. Changes in biochemical parameters were preceded by an increase in AspAT activity and were most remarkable between 48 and 144 hours after saccharose administration. Liver dysfunction was of a various degree in individual animals and recovered within a relatively short period following the disappearance of rumen acidosis symptoms.