This work presents the continuous, multistage aqueous two-phase extraction of an Immunoglobulin G1 from a Chinese Hamster Ovary cell supernatant. An aqueous two-phase extraction process combining a sodium chloride-rich extraction step, followed by a sodium chloride-poor back extraction and washing step is investigated experimentally. A polyethylene glycol 2000-phosphate salt aqueous two-phase system was applied for extraction. Different process configurations determine the influences of flow rates, stage number and cell supernatant loading. Immunoglobulin G1 yields of up to 88% and purities of up to 95% are obtained and indicate the potential of continuous, multistage aqueous two-phase extraction. To reduce the raw material consumption recycle batch experiments are conducted to analyze the influence of phase recycling on the extraction performance. Phase recycling is also carried out at multistage scale. An equilibrium stage model is developed and successfully validated within this work. The model is able to predict the continuous, multistage aqueous two-phase extraction on the basis of single stage equilibrium data representing a useful tool to decrease experimental process development effort. (C) 2015 Elsevier B.V. All rights reserved.