Electrochemical properties of heterogeneous anion-exchange membranes can be indicators of their fouling during electrodialysis of phenylalanine solutions. The current-voltage curves of the membrane MA-40 make it possible to reveal the difference in the limiting current values for fresh and fouled membranes. Increase of membrane voltage with time characterizes the development of fouling in the electromembrane system. Membrane conductivity decreases significantly in solutions containing phenylalanine. Overlimiting current conditions lead to "washing out" of amino acid from membrane phase and therefore help to avoid fouling. (C) 2011 Elsevier Ltd. All rights reserved.