Fibrinogen, albumin and the major apoprotein of high density lipoprotein (apoprotein A) were localized in a primary embryonic chick liver cell culture by indirect immunofluorescence staining. Changes in the pattern of plasma protein synthesis under a variety of conditions, as measured by the accumulation of secreted plasma proteins in the culture medium, could be studied at the cellular level because relative fluorescence intensities were shown to reflect synthetic rates. In all cases studied, the immunofluorescence of the hepatic parenchymal cells was of a similar intensity throughout the monolayers, indicating that the cells in culture constitute a homogeneous population with respect to the synthesis of these plasma proteins.