Naphthol AS-BI phosphatase, esterase, aryl sulphatase, glucuronidase, and β-glycerophosphatase have been studied in frozen sections of maize root tips. In general these enzymes showed highest activities at the root surface and at particulate sites in the cytoplasm although the indigogenic method for esterase showed no particulate activity and the naphthol AS-D acetate reaction gave no pronounced surface activity. With electron microscopy highest activity for β-glycerophosphatase was observed in the cell walls and associated with the vacuoles. The significance of these observations are discussed in relation to the function of surface hydrolytic activity and to the presence of lysosome-like bodies in higher plant cells.