The hypersensitivity reaction in Nicotiana tabacum var. Xanthi n.c. infected with Tobacco mosaic virus (T.M.V.) leads to the production of aromatic amides (ferulylputrescine, diferulylputrescine, p-coumarylputrescine and di-p-coumarylputrescine) inthe cells around the necroses. Similar compounds are formed in Xanthi plants after floral induction. p-coumarylputrescine, di-p-coumarylputrescine and caffeylputrescine strongly inhibit T.M.V. multiplication.