Furuya, T., Nakada, K., Iwai, Y., Arai, Y. and Takeuchi, K., 1990. Measurement and correlation of phase equilibria of aqueous two-phase systems and partition coefficients of enzymes. Aqueous two-phase systems provide a successful method for separating biomolecules by extraction under mild condition. Nevertheless, the phase equilibrium data of aqueous two-phase systems and the partition coefficient data of biomolecules are scarce and it is difficult to correlate them quantitatively. In the present work, the phase equilibria for the dextran-polyethylene glycol-water aqueous two-phase systems are measured. The partition coefficients of enzymes are also measured. Further, the osmotic virial equation is used to correlate the phase equilibria of the aqueous two-phase systems and the partition coefficients of enzymes.