Glycerophosphatase activity has been studied in frozen sections of maize, barley, and broad-bean root tips by the Gomori lead sulphide precipitation procedure. The enzyme was largely localized at particulate sites in the cytoplasm, and in the cell walls. In maize and barley the particles were similar to acid phosphatase-containing spherosomes found in other tissues and were most active in the cortical cells. The wall reaction was highest in the outer cells, in agreement with biochemical studies. When excised roots were incubated in the Gomori medium, staining was restricted to the surface cells. The possible function of this surface activity and its relevance to ultrastructural studies is discussed.