Chemical analysis of adult cat prostate shows that zinc is present in significant amounts. Attempts to demonstrate the zinc at cell level using dithizone give indeterminate results. From autoradiographs, the zinc is scattered throughout the cell but concentrated in the apical area, along the luminal surface, and free in the lumen. Electron micrographs of the acinar cell show secretory granules agreeing with the grain distribution of the autoradiograph. Previous histochemical findings gave a similar position for non-specific acid phosphatase and 5-nucleotidase. It is suggested that zinc is an integral part of the secretion of the cat prostate, and associated with the production of metalloenzymes.