AbstractABSTRACT The Influence of dimethyl sulfoxide (DMSO) concentrations from 0 to 22% (v/v) was studied on the electrophoretlc nihilities, the droplet formation times, the cell sedimentation rates and the cell sedimentation volumes of fresh and aldehyde-fixed human erythrocytes and on fixed turkey erythrocytes.DMSO influenced the ζ-potentials of the different cells in various ways. These observations remain phenomenoncgical for the time being; it Is not as yet possible to predict quantitatively how the ζ-potentials of given cell types will be affected by the admixture of DMSO.Low concentrations of DMSO (up to 7.5%) cause red cells to swell, resulting in an Increase in sedimentation velocity due to their increased Stokes radius. At higher DMSO concentrations no further swelling occurs so that, due to a decrease in density difference between the cells and the liquid medium, the sedimputation velocities then decrease, Cell sedimentation volumes and droplet formation times reached maxima at 13% DMSO (for fixed human cells) and at 10% (droplet formation times) to 12% DMSO (sedimentation velocity) for fixed turkey cells. DMSO uptake by cells, resulting In volume and/or density changes, must be taken into