The present study demonstrates an altered distribution pattern of anionic sites of the human erythrocyte glycocalyx. The findings prove a significant rearrangement of membrane constituents induced by a digitonin treatment of aldehyde fixed red blood cells. The effect is not confined to lipids and, presumably, it causes the loss of lipidic and nonlipidic membrane components. It can be deduced that the fixation with a mixture of formaldehyde and glutaraldehyde insufficiently stabilizes the membrane structure.