Use of alginate as a free bioligand incorporated in an aqueous two-phase system of polyethylene glycol 6000–salt resulted in considerable purification of wheat germ α-amylase and sweet potato β-amylase from their crude extracts. The elution of the enzyme from the free bioligand was facilitated by exploiting the fact that alginate can be reversibly precipitated in the presence of Ca2+. α-Amylase could be purified 42-fold with 92% activity recovery. β-Amylase on the other hand could be purified 43-fold with 90% recovery. Both purified enzymes showed a single band on sodium dodecylsulfate–polyacrylamide gel electrophoresis.