Amphiphilic A-B block copolymers, omega-methoxypoly(ethylene oxide)-amylose copolymers (MPEO-amylose), were synthesized by an enzymatic reaction using potato phosphorylase from an MPEO ((M) over bar(w) = 5.0 x 10(3))-maltopentaosylamine derivative as a primer and alpha-D-glucose-1-phosphate as a substrate. MPEO-amyloses with various molecular weights of amylose (DP = 26, 36, 73 and 112) were obtained. None of the MPEO-amyloses (5 mg/ml) precipitate in water containing 10 vol.-% DMSO even after 24 h. The MPEO-amyloses effectively form complexes with iodine in water.