AbstractDistribution of starch components of maize (Zea maysL.) and their properties were investigated by gel filtration after debranching and by exhaustive hydrolysis of starch‐granules with glucoamylase. Based on the results, relationship between genotypes and properties of starch components were discussed.Thesugary‐1 (su1),sugary‐2 (su2), anddull(du) mutants produced high amylose maize, while amylopectin ofsu2was normal type and those ofsu1andduwere novel type. In the double‐mutant combinations, thewaxy(wx) gene decreased amylose content. Starches ofdu su1ordu su2possessed greatest amount of amylose among starches examined. Contents of amylose, intermediate fraction (Fr.) and longer branches of amylopectin increased in most cases when theamylose‐extender (ae)gene was introduced. Starches ofaepossessed longer average chain‐lengths of amylopectin than that of normal. Inae dustarches, however, elongation of the amylopectin chain and increase of the intermediateFr.did not occur. Exhaustive degradation of starch‐granules by glucoamylase showed thataestarches were more resista