Antioxidative activity of acetyl salicylic acid, indometacin, ibuprophen, orthophen, delagil, D-penicillamine and levamysol was studied under conditions of NADPH- and CCl4-dependent lipid peroxidation both in rat liver microsomes and in adrenaline autioxidation. All the drugs studied exhibited only slight antioxidative activity being dissolved in mater, and especially towards lipid peroxidation, as compared with quercitrol and ionol; their activity was noted at concentrations exceeding distinctly the therapeutic doses. At the same time, D-penicillamine inhibited lipid peroxidation not only by means of free radicals neutralization but also via binding of iron ions. This property of the drug may be responsible for its effects, to some extent, in treatment of joint inflammations.