Cells may be thawed, selected, expanded, genetically altered, differentiated, and/or cryopreserved prior to use for cell therapy. Each step may require a different medium or buffer that may contain substances that can harm the cells. The Gibco™ CTS™ Rotea™ Counterflow Centrifugation System can effectively remove residual substances. Wash buffer can be pumped through the fluidized bed to replace the medium used to load the cells, and over 95% of residual substances can be removed with minimal cell loss. Here we describe how the CTS Rotea system can be" used to efficiently remove various residual substances from T cell culture medium. Washing T cells to remove impurities helps make the cells safer and more useful for downstream applications. The cell washing and concentration workflow for the CTS Rotea system is outlined below.