Malonate was tested for its effects on rat hepatic metabolism of [1,4-14C]-succinic acid and [1-14C]-glycerol. The administration of malonic acid did not limit [1,4-14C]-succinate metabolism and change the rate of radioactive labelling from [1-14C]-glycerol to the total lipid fraction, as well as the fraction of phospholipids and triacylglycerides. However, there was a reduction in the use of glycerol as a precursor of higher fatty acids and cholesterol. It is suggested that the detected effect of malonate is due to its action on oxidative decarboxylation of pyruvic acid.