EN
2-/4-/2-(4-chlorbenzamido) ethyl/phenoxy/-2-methyl-propionic acid (CBMP) reduced the intensity of cytopathic effect, delayed the time of its appearance for 24—48 hours and finally caused a significant lowering of ТСID₅₀ titer of herpes simplex in monkey kidney cell cultures and of pseudorabies virus in chick embryo cell cultures. On the other hand CBMP did not exert any effect on the multiplication of Roakin strain of NDV in chick embryo cell cultures. The preparation did not inactivate directly the viruses being examined and did not influence their adsorption. It is suggested that antiviral effect of CBMP is due to disordering the lipid metabolism in cells what causes the disturbances of virus envelope synthesis.