In order to perform comparative studies of the cardiac myosin heavy chain (MyHC) genes, we determined the sequence of the Syrian hamster beta-MyHC gene and its 5' flanking region. This 33,960 basepair (bp) sequence contains 12,196 bp of the 5' flanking region as well as 21,731 bp of the complete beta-MyHC gene, with its 3' end overlapping with the alpha-MyHC gene. All the exon/intron boundaries were determined and relative to the human beta-MyHC gene, an extra 5' untranslated exon was identified. The isolation and sequencing of the Syrian hamster beta-MyHC gene may further the understanding about the regulation and the evolution of the cardiac MyHC genes.