A quick-freezing and deep-etching method in combination with erythrocyte splitting was used to examine the cytoplasmic aspect of whole-mount human erythrocyte membranes. Various external forces induced alterations in membrane skeletal organisation during the splitting procedure. The initial change was elongation in the peripheral part of the membrane skeleton, examined by immunostaining with a monoclonal antispectrin antibody. Under severe stretching conditions, a linear rearrangement of filamentous components was evident; these were disposed parallel to the rim of the erythrocyte, while the central part of the concavity exhibited a more compacted structure. These changes resulted in a different distribution of membrane skeletal components between central rigid and peripheral flexible areas in biconcave erythrocytes. It is suggested that the reversible membrane skeletal changes in the flexible areas which resist the external forces are important for maintaining the normal framework of biconcave human erythrocytes.