The effect of eight ethylenediamine and ethanolamine derivatives on inflammation was investigated in the carrageenan-induced rat paw edema model. The ability of these compounds to inhibit superoxide anion radical (O2-.) formation in vitro was also examined using the xanthine-xanthine oxidase system. Almost all of these substances were found to possess anti-inflammatory activity. This action can be well correlated with their reported capacity to inhibit microsomal membrane lipid peroxidation, while they demonstrated negligible effect on O2.- generation. The above actions appear to depend on some structural characteristics, particularly in the aromatic series of compounds.