The morphology of CSF cells changes in vitro rapidly. An optimal cytologic evaluation therefore requires special demands for the cell preparation. The cell concentration by means of the forced spontaneous sedimentation yields the best cytomorphologic results. A simple method for cell concentration has been described. Its application in two variations is determined by the cell content. In the first version the cells sediment spontaneously on the microscopic slide and in the second version on the membrane filter. The sedimentation is facilitated by the absorbent paper. This method is particularly suited for concentrating cultured cells and CSF cells, which have been incubated in the presence of tracer.