Fluid secretion by exocrine glands requires the coordinated activity of multiple water and ion transporter and channel proteins. The molecular cloning of many of the transporter molecules involved in fluid secretion has yielded a better understanding of the fluid secretion process. Mouse salivary glands are easily accessible model systems for the study of exocrine gland secretion at the cellular and organ level. Indeed, the characterization of mice with null mutations in many of the water and ion transporter and channel genes has demonstrated the physiological roles of individual proteins. This overview will focus on recent developments in determining the molecular identification of the proteins that are involved in the fluid secretion process. J. Med. Invest. 56 Suppl.: 192-196, December, 2009