Effects of some dietary o-dihydroxyphenols on biochemical markers of oxidative stress within tissues of Sitobion avenae (Fabricius), (Homoptera, Aphididae) and Rhopalosiphum padi (Linnaeus), (Homoptera, Aphididae) has been studied. Among the studied aphid morphs the highest concentration of total thiols, hydrogen peroxide and lipid peroxidation products (TBARS) was noted for winged adults (alatae). Higher content of H2O2 was observed within tissues of the oligophagous species R. padi while the monophagous species S. avenae had higher TBARS and total thiols concentration. Aphids exposed the dietary pro-oxidative o-dihydroxyphenols (quercetin, caffeic acid, chlorogenic acid) demonstrated significantly lower concentration of total sulfhydryls and higher level of TBARS and H2O2 than the control ones. Among the studied compounds, chlorogenic acid showed the strongest effect on the level of thiols and TBARS while caffeic acid caused the highest accumulation of the hydrogen peroxide within the aphid tissues.