Acid fast staining of the bleached residuum of substantia nigra neuromelanin and of oxidized inferior olive lipofuscin was demonstrated in paraffin and frozen sections stained with the acetic acid, carbol fuchsin method of Barbeito-Lopez and the aldehyde fuchsin method of Gomori. Acid fast staining occurred when sections were exposed to a prestain oxidation with potassium permanganate in conjunction with a poststain differentiation with dilute hydrochloric acid. The acid fast staining with acetic acid, carbol fuchsin was differentiable and in contrast to the acid fast staining with aldehyde fuchsin which was nondifferentiable. A possible histochemical basis for differentiable and nondifferentiable acid fast staining was discussed. The identity of the bleached residuum of neuromelanin as lipofuscin was also discussed.