Monoclonal antibodies (mAbs) are the most important family of biopharmaceutical compounds in terms of market share. At present, 30 mAbs have been approved and are now commercialized for therapeutic purposes. mAbs are typically produced by mammalian cell culture in bioreactors that range in scale of 120 m3. Regardless of scale, from laboratory to commercial settings, the recovery and purification of mAbs present important challenges. Depending on the scale, the particular product, and the type of production process (bioreactor operation, process time, complexity of the culture media, cell density, etc.), many possible downstream configurations are possible and have been used. In this contribution, we review each type of unit operation that forms a downstream train for mAb production. We provide information regarding typical operation settings and critical variables for centrifugation, ultrafiltration, affinity chromatography, ion exchange chromatography, and viral removal operations. In addition, we discuss some important considerations required for the formulation of drugs based on mAbs. (c) 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 899916, 2012