AbstractStarches from ten yam (Dioscorea) species were compared with those of maize, wheat, potato and cassava, and characterized by high‐performance size‐exclusion chromatography coupled with multiangle laser light scattering. Treatment with 95% (v/v) dimethylsulphoxide and microwave heating in a high‐pressure vessel led to complete dissolution of the starch samples. For yam starches, M̄w were between 1.88 × 108 and 3.27 × 108 g mol−1 and R̄G were between 258 and 396 nm. The hydrodynamic coefficients of amylopectins were between 0.36 and 0.44, indicating that those of maizes and esculenta 5 and dumetorum yam species had particularly highly branched structures. Multidimensional analysis of the macromolecular characteristics of yam starches indicated three classes: dumetorum cultivar (Dioscorea dumetorum), esculenta 5 cultivar (Dioscorea esculenta) and the other eight yam starches, including cultivars of Dioscorea alata and Dioscorea cayenensis‐rotundata species. Some yam starches were also leached at 90 °C. The macromolecular characteristics of the leached fractions confirmed the previous typology. Copyright © 2003 Society of Chemical Industry