Patients 4 years of age and older with dry mouth symptoms and a diagnosis of primary, secondary or incomplete Sj(SqrRoot)(Delta)gren s syndrome or salivary gland dysfunction due to radiation may be eligible for this study. Candidates will be screened with a complete medical and dental history and blood and saliva tests. Some patients will have a biopsy of the minor salivary glands, usually from the lower lip, to confirm or rule out the diagnosis of Sj(SqrRoot)(Delta)gren s syndrome and determine the extent of changes in the salivary glands. (A biopsy is the surgical removal of a small piece of tissue for laboratory examination.) The ability to taste and smell may also be evaluated, and patients may have an ultrasound examination of their swallowing function.