The host-plants of bird cherry-oat aphid were compared as to the content and composition of phenolic compounds. The gallic, chlorogenic, caffeic, siringic, o- and p‑coumaric, tannic, ferulic, sinapinic, salicylic, p‑hydroxybenzoic acids and /+/‑catechin were detected in the all studied host-plants of the bird cherry-oat aphid. Coumarin and vanilic acid only occurred within orchard grass and winter triticale tissues. Predominant compounds within P. padus leaves were /+/‑catechin, chlorogenic acid, p-hydroxybenzoic acid and tannic acid. Vanilic and salicilic acids were the major compounds of the orchard grass, whereas leaves of winter triticale contained mostly salicilic, chlorogenic and vanilic acids as well as coumarin. Key words: phenolic compounds, Prunus padus, Dactylis glomerata, triticale, bird cherry-oat aphid, HPLC