Retrovirus-like particles (RVLPs) that are expressed during the production of monoclonal antibodies in Chinese hamster ovary (CHO) cell cultures must be removed during product recovery. Anion exchange chromatography (AEX) performed in product flow-through mode, a common, component in the purification of monoclonal antibodies, has beet? shown to provide robust removal of a related retrovirus model, but it's ability to remove the actual RVLP impurities has not been directly investigated. We have determined the ability of a typical Q sepharose process to remove actual CHO RVLP impurities. Using small scale experiments with three model antibodies, we observe that this AEX process is capable of effectively removing both in-process and spiked RVLPs from? different feedstocks containing different mAb products. In addition, we show that this AEX process also achieves a similarly high degree of RVLP removal during large scale manufacturing operations. (C) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 25: 1194-1197, 2009