Abstract: The instant invention is directed to the use of a biologically compatible composition, containing an effective amount of a metal-independent nitroxide compound which is preferably represented by the formula wherein R1 is —CH3; R2 is —C2H5, —C3H7, —C4H9, —C5H11, —C6H13, —CH2—CH(CH3)2, —CHCH3C2H5, or —(CH2)7—CH3, or wherein R1 and R2 together form spirocyclopentane, spirocyclohexane, spirocycloheptane, spirocyclooctane, 5-cholestane, or norbornane, R3 is —O. or —OH, or a physiologically acceptable salt thereof, and a pharmaceutically acceptable carrier, as antioxidants capable of protecting cells, tissues, organs, and whole organisms against the deleterious effects of harmful free radical species generated during oxidative stress.