It is well known that both tocopherols (T) and tocotrienols (T3) act as radical-scavenging antioxidants. The reactivities of β, γ, and δT and the corresponding T3 isoforms toward free radicals are the same, and the corresponding T and T3 inhibit lipid peroxidation in solution similarly. T3 has a higher mobility between membranes and a higher rate of incorporation into membranes than does T. The initial rate of cellular uptake of T3 is higher than that of T, which confers an apparently higher cytoprotective capacity to T3 compared with T. The incorporated T and T3 are distributed proportionally to the lipids in the cells and function as radical scavengers to prevent lipid peroxidation and cell death. Oxidized products of vitamin E, such as tocopheryl quinone, have unique chemical and biological properties as arylating or non-arylating quinone. In this chapter, the chemical reactivity and cytoprotective effects of T and T3 are comparatively described.