More than 15 years ago a pioneering report on the separation of cellular material using sedimentation field-flow fractionation (SdFFF) was published. Surprisingly, only a few reports on SdFFF applications to cell separations are available as yet. The major limitations which seemed to slow the development of SdFFF applications in biology appeared to be related to the development of specific instrumentation. Therefore, guidelines are given for setting up a biocompatible SdFFF apparatus. SdFFF elution of cells with different characteristics was performed to demonstrate the efficiency, completeness, and rapidity of cell separations by this method. Retention data describing the effect of lifting forces on nucleated cells are compared to those for red blood cells (RBC). The effects of flow rates, field intensity, and injection protocol were studied using normal human RBC eluted in isotonic medium as a probe for retention conditions. When possible, data were also compared to previously published reports. Guidelines for elution and separation optimization are given. Using mixtures of nucleated and living red blood cells, viability studies showed a surprisingly high recovery of each type of material.