The diminution of neuronal lipofuscin was studied in centrophenoxine adminstered animals. In fluorescent studies, as well as in ordinary histological methods, a marked decrease of the lipofuscin was observed in the cerebral cortex, hippocampus, thalamus, basal ganglia, midbrain, medulla oblongata and spinal cord. The lipofuscin in the cenntrophenoxine animals showed fine granular structures in the perikarua of the neurones when compared to that of control rats. Electronmicroscopically, electron density of the lipofusin structures was observed. Enlargement of the vacuolar portions of the lipofuscin was seen in the neurones of the dorsal ganglia in the centrophenoxine animals. In the present studies, the diminution of the lipofuscin in the neurones was well demonstrated with fluorecent and histological methods. The characteristic ultrastructural changes of the neuronal lipofuscin are reported.