Summary Further evidence is presented that the receptor induced on the surface of cells infected with herpes simplex virus is specific for the Fc fragment of the IgG molecule of several species. A method has been developed for quantitative studies of this receptor using rabbit IgG labelled with [125I]. The effects of actinomycin D, puromycin, and cytosine arabinoside on the development of the receptor during the virus growth cycle are described. Evidence was obtained of a turnover of membrane receptors after infection.