The partitioning of alcohol dehydrogenase glucose-6-phosphate dehydrogenase and hexokinase from pressed bakers’ yeast was studied in polyethylene glycol (PEG)/potassium phosphate aqueous two-phase system using unbound reactive triazine dyes as affinity ligands. The various parameters investigated were ligand type and concentration, pH of the system, phase composition of the system, and molecular weight of PEG. It was found that the best ligands gave an increase in partition coefficient of 2 to 3 times over that in the absence of the ligand.