Genes controlling the synthesis of the D group of low-molecular-weight (LMW) subunits of glutenin occur on the short arms of chromosomes 1B and 1 D. Their position on chromosome 1 B, relative to the storage protein loci Glu-B1 (long arm) and Gli-B1 (short arm), was estimated by analysing the backcross-one progeny of two different crosses. To estimate recombination between the D subunit genes and Gli-B1, half grains were analysed by two-dimensional electrophoresis. The Gli-B1 locus contains genes for the B group of LMW glutenin subunits, γ-gliadins and ω-gliadins although only the latter were made use of in this study to distinguish the parental alleles. Additionally, the complementary half grains were analysed by sodium dodecyl sulphate, polyacrylamide-gel electrophoresis to estimate recombination between Gli-B1 and Glu B1, coding for high-molecular-weight (HMW) glutenin subunits. The D subunit genes occur at a new locus, provisionally defined as Glu-B2, which lies in between Glu-B1 and Gli-B1, 17 cM from the former and 22 cM from the latter. On the basis of previous mapping data involving Gli-B1, it was concluded that the D subunit genes occur close to the nucleolar organizing region and probably on the short-arm satellite, like Gli-B1.