Using a unique set of deletion lines, (Olympic×Gabo, varying in high molecular weight glutenin subunit (HMW-GS) composition, but with the same genetic background) it was shown that the presence of glutenin particles in glutenin macropolymer (GMP) is directly related to the presence of certain HMW-GS. In the absence of HMW-GS only a small amount of insoluble glutenin protein (GMP) could be recovered from the flour that contained only LMW-GS. No particles were observed in this fraction. When one subunit (HMW-GS Glu-Ax1) was present some particles could be observed, but when two or more HMW-GS were present particles could be clearly identified. The amount of GMP increased with the increasing number of HMW-GS. All particles had the same LMW-GS composition irrespective of HMW-GS-composition. Since the relative proportion of LMW-GS in GMP was dependent on the number of HMW-GS, we postulate that LMW-GS become part of GMP through disulfide cross-linking with HMW-GS. GMP wet weight is correlated with the average HMW density of the glutenin particle. These data were combined with previously published technological data from the same set of wheats. Significant statistical relationships were observed between optimal mixing time and glutenin particle size and between thimble-loaf height and GMP content. Taken together, these studies suggest that glutenin HMW-GS composition affects flour technological properties through glutenin particle size. © 2006 Elsevier Ltd. All rights reserved.