To provide methods for the crystallization of macromolecules in a three-phase system, appropriate devices, a three-phase system, and the use thereof in automated crystallization methods.

The method for the crystallization of macromolecules in a three-phase system uses a vessel containing a lower aqueous phase, a middle phase and an upper hydrophobic phase having a lower density than that of the lower aqueous phase, wherein an aqueous solution of the macromolecules is added to the middle phase to form a fourth phase, followed by incubation. The macromolecules, in particular lysozyme, glucose isomerase and xylanase, are crystallized.