The presence of zinc in the mossy fibre system of the Hippocampus is the most thoroughly studied of zinc relation to the CNS, but many other areas of the CNS are zinc-containing. Many methods have been used in order to investigate the above mentioned relation, most of them being based on histochemistry and physical measurement. 65Zn trace has also been used, but scarcely, probably due to the difficulty of radioisotope handling. In the present review we focus on 65Zn studies in the CNS and comment on their advantages and disadvantages.