After the era of genome, proteome era has come. In relation to protein conformation, interests toward the roles of water surrounding biomolecules are rapidly growing. Recently, several workshops and symposia have been held on the interplay between biomolecules and their surrounding water. This movement stimulated this symposium, which focuses on the structural and functional significance of water at a larger scale; subcellular to tissue size. I would like to ask all of you to reconsider active roles played by water in the tissue or cells of your concern. [Jpn J Physiol 55 Suppl:S46 (2005)]