A method for separation of isolated cells according to their characteristic sedimentation rates in a centrifuge rotor which is designed to allow flow-through of a fluid during operation; also known as countercurrent elutriation and elutriation centrifugation. The centrifugal force on the cells is opposed by the force of a fluid moving in the opposite direction. Cells are first sedimented in a density gradient, then displaced by a buffer of increasing density that flows into the bottom of the sample cell and out of the top, and carries with it cells of the same density.