The Lesch-Nyhan syndrome is commonly regarded as a metabolic disorder of the purine metabolism without specific morphological changes. In the present paper a report is given on a 13-year-old boy. The neuropathological investigation revealed PAS positive deposits in the ganglion cells of the nucleus olivaris. In HE preparations, the storage material appears as light foamy accumulations displacing nuclei to the cell border. The deposits are sudan-III-negative and there is no UV fluorescence. Electron microscopically the primarily formol fixed tissue of the nucleus olivaris shows circumscribed accumulations of a relatively homogeneous substance with medium density in the dilated smooth endoplasmic reticulum. The diameter ranges from 476 to 850 nm. In this connection, it seems to be possible that the lack of cGMP might lead to disturbances of the protein metabolism of postsynaptic structures, the significance of which is discussed. It is suggested that further investigations of the CNS in Lesch-Nyhan patients should be focussed on the nucleus olivaris.