1. alpha-Amylase immobilized on polyamide 11 showed higher specific activity and retention of activity than the derivatives employing polyacrylamide and polyethyleneterephthalate as supports. 2. Polyamide 11 and polyethyleneterephthalate alpha-amylase derivatives exhibited a higher extent of multiple attacks on starch than the water-soluble enzyme whereas the polyacrylamide derivative presented less. 3. The polyamide 11 alpha-amylase derivative acted on amylose-azure in the same way as the water-soluble alpha-amylase.