The properties of alkaline phosphatase present in Taenia crassiceps cysticerci were studied. Approximately a half of the total activity was free and the remaining part was bound to membranes. Kinetic studies did not show any differences between the free and bound alkaline phosphatases. It was found that high substrate concentrations produced an inhibitory effect on the enzyme. This effect was much greater at lower pH. pH optimum changed with the concentration of the substrate.