The lead method and the calcium method of Wachstein and Meisel and Padykula and Herman respectively have been applied to cryostate sections of the human skin and the results have been compared. It is concluded that the lead method is preferable for the demonstration of ATP-ase for routine use. Nice staining results are obtained if magnesium nitrate, instead of magnesium sulphate, is incorporated in the basic incubation medium. At least 6 phosphate compound hydrolyzing enzymes have been shown to be present in the skin. An enzyme capable of hydrolyzing a polyphosphate with short chain length (3 monomers) was found to be localized in the capillaries of the cutis, the arrectores pilorum muscles, the granular layer and the inner hair sheath. The staining results were described and compared. Dendritic cells (presumably Langerhans'' cells) are nicely stained when ADP, ATP, and ITP were respectively used as substrates. The results obtained after pretreatment with inhibitors and after incorporation of these compounds in the reaction medium, suggest the existence of more phosphate splitting enzymes.