Liver slices from normal rats and those suffering from inflammation for 24-48 h were incubated with L-[-14C]leucine or D-[-14C]glucosamine. Immunological techinques coupled with radioautography indicated that the microsome fraction prepared from slices contained the subcellular site of synthesis of the polypeptide chain of serum albumin, and the polypeptide and carbohydrate chains of alpha-1-acid glycoprotein; both proteins were also present in the medium in labelled forms. The contents of albumin and alpha-1-acid glycoprotein in the medium and in extracts of liver from experiments with liver slices from control rats and 8-72 h experimental rats were determined using the quantitative precititin technique. There was a net increase in synthesis of both proteins when slices from control and experimental animals were used, the increase showing up in medium protein. However, slices from livers from 8-72 h experimental rats had a greater capacity for synthesis of alpha-1-acid glycoprotein and lower capacity for synthesis of albumin than slices from livers from control rats, the greatest changes occurring with slices from 24 h experimental rats. Changes in synthetic capacities of liver slices from experimental rats for albumin and alpha-1-acid glycoprotein were always accompanied by large increases in specific radioactivities of total medium proteins when experiments involved incubation of slices with L-[-3H]leucine and D-[-14C]glucosamine. It is suggested that the increase in specific radioactivities of medium proteins following incubation of liver slices from experimental rats with labelled leucine and glucosamine is a characteristic of the response of liver to inflammation, and reflects changes in the capacity of liver for the synthesis of alpha-1-acid glycoprotein and other acute phase serum proteins.