Isoelectric focusing and concanavalin A-Sepharose chromatography were used to study the multiple forms and glycoprotein natures of so-called lysosomal hydrolases from psoriatic scales. Acid phosphatase appeared as 5 different forms with pI values of 6.5, 6.1, 5.8, 5.6 and 5.45. Seven isoenzymes of alpha-fucosidase were identified with pI values of 6.4, 6.2, 5.9, 5.75, 5.65, 5.4 and 5.2. Acid alpha-mannosidase activity appeared as one peak with pI value of 6.75 and a weak activity of neutral alpha-mannosidase was present with pI value of 6.7. Incubation of the extract with neuraminidase increased their pI values of acid phosphatase, alpha-fucosidase and alpha-mannosidase to the more basic forms. This finding suggests that epidermal acid phosphatase, alpha-fucosidase and alpha-mannosidase have some N-acetylneuraminic acid residues. In addition concanavalin A-Sepharose column chromatography was also performed to confirm the glycoprotein nature of acid phosphatase. This enzyme was bound to the column and not released from the column even with the treatment of 0.5 M NaCl, but the enzyme was eluted from the column with the treatment of alpha-methyl-D-glucoside.