Using triamcinolone acetonide C14 solution and the cellophane tape stratum corneum stripping technique, the corticosteroid reservoir of Vickers in the stratum corneum after polyethylene film occlusion was confirmed and quantitated. The intact stratum corneum is an excellent barrier against this corticosteroid, confining most of it to the outermost horny layers. Dermal vasoconstriction is an extremely sensitive physiologic marker for the presence of minute amounts of corticoids. Incidental findings included the presence of a mild dermatitis after plastic wrap occlusion in areas not treated with corticosteroid and increased ease of stratum corneum removal after such an occlusion.