Quantitative and qualitative measures of liver function were investigated in rabbits with chronic renal failure (CRF) induced 3 months earlier by surgical reduction of renal mass, and compared with a sham-operated control group. In the CRF group the galactose elimination capacity (GEC) was significantly decreased by 25%, but when related to liver weight the difference was not statistically significant. The clearance of antipyrine was unaffected. The serum activities of alanine aminotransferase, lactate dehydrogenase and alkaline phosphatase were similar in the two groups. The prothrombin index was increased by 20%, and the serum albumin concentration decreased by 9%. By light microscopy no significant morphological changes were found in the livers of the CRF rabbits. The results do not indicate significant changes of the hepatic functional status during moderate chronic renal insufficiency.