A new technique for crystallizing proteins is introduced. Solvent removal by freezing-out is employed to crystallize hen egg white lysozyme from aqueous salt solutions. The crystallization is carried out at moderate salt concentrations (1-10 wt% NaCl) and at pH 4.4-5.2. The required supersaturation for nucleation and crystal growth is achieved by removal of the solvent resulting in a concentration increase with respect to salt, buffer, and protein. A simple tube and shell heat exchanger is used to generate the driving force for crystallization of the ice. The enzymatic activity of the resulting crystals is measured after their dissolution and shows large variations with respect to the crystallization conditions, though no systematic behavior is observed. The effect of the cooling rate applied to the cold finger upon the protein concentration in the ice is investigated.