Bivalves are the second largest class of living mollusks, which in turn constitute the second largest animal phylum. Little research has focused on this particular group of animals. Moreover, many of the bivalve studies carried out to date have been limited to a few ecologically important model species. Studies on a broader range of bivalve species would enable a better understanding of the phylogeny, speciation and diversification of bivalves. However, research on this group of animals has long been suffered challenges for systematic biology studies due to the lack of genomic resources. We performed de novo transcriptome sequencing in a cold water bivalve species, the Yesso scallop (Patinopecten yessoensis), using the Roche 454 GS FLX platform. The produced data provide the most comprehensive sequence resource currently available for the Yesso scallop. The analysis results obtained led to novel findings related to gene expression in different tissues and to an extensive collection of potential genetic markers for population and association studies. The EST collection is a much-needed genomic resource for this non-model species, which will provide insight into the evolutionary and biological complexity of scallops, and serve as a physiological and genetic basis for the management of its breeding program.