This study examined the effect of aminoguanidine (AG) and its structural analogs semicarbazide (SK) and thiosemicarbazide (TSK), as well as their condensation products with 2,4-dihydroxybenzaldehyde-resorcylidene aminoguanidine (RAG), resorcylidene thiosemicarbazone (RTSKon), and resorcylidene semicarbazone (RSKon) on erythrocyte lipid peroxidation in rats with diabetes mellitus induced by hydrogen peroxide. All of the tested compounds at concentrations 1 mmol.l-1 in incubation mixture significantly inhibited the formation of malondialdehyde (MDA), an end product of lipid peroxidation, as assessed by its thiobarbituric acid reactivity. AG and RAG were the most effective inhibitors of lipid peroxidation 90%). It was also found, that RSKon and RTSKon were more potent inhibitors of lipid peroxidation (70 and 80%) compared to Sk and TSK (50%). We suppose that this increase of inhibitory effect by compounds with resorcylidene group may be due to the formation of quinone structure.