Allelic diversity and inheritance of polymorphic sites of the intron III-exon IV region of the seed specific beta-amylase gene Bmy1 were studied in a set of 55 barley accessions composed mainly of old Latvian and Scandinavian commercial varieties and three Hordeum spontaneum lines from Israel. A CAPS-marker was used for genotyping the C698 --> T polymorphism encoding alleles of beta-amylase with different thermostability. The genotype C698 which is diagnostic for a more thermostable isoform of the beta-amylase was detected in 13 of the investigated accessions. In most cases the origin of the C698 genotype could be traced back to the old Danish variety Binder in the pedigree. However, this genotype was lost in later varieties originating from Binder. A 6+1 bp deletion event in intron III of the beta-amylase gene was in all cases linked to the presence of the C698 mutation, while the repeat number of a microsatellite in intron III had no correlation to the presence of the C698 mutation. Sequence analysis revealed a number of haplotypes within exon IV that did not result in amino acid changes due to the degenerated genetic code.