Abstract: A method and adsorption medium for isolating and purifying enzymes from a crude enzyme solution of animal organs or tissues. An adsorption medium for bringing about the binding of a predetermined enzyme is introduced into the crude enzyme solution and is left therein until the binding takes place, whereupon the adsorption medium is removed from the crude enzyme solution and the enzyme is separated from the adsorption medium by extraction or elution with a suitable solution. The adsorption medium is in the form of membranes of human or animal erythrocytes which have been hemolyzed by osmosis. Those enzymes which have the same or nearly the same affinity as regards binding on the membranes as does the predetermined enzyme which is to be bound are separated from the membranes prior to introducing the membranes into the crude enzyme solution. The amount of the enzymes first removed that is bound being less than the amount of erythrocytes used to form the membranes.