* INCLUSION CRITERIA: 1. 18 years of age or older. 2. Capable of providing informed consent. 3. History of radiation therapy for head and neck cancer, having received \>45Gy to the parotid gland(s) due to primary or neck radiation. 4. Abnormal parotid gland function in the targeted parotid gland as judged by absence of unstimulated parotid salivary flow and a stimulated parotid salivary flow in the targeted parotid gland \<0.2 mL/min/gland after 2% citrate stimulation. 5. Abnormal (99m)TcO4 scintiscan (reduced or absent uptake of (99m)TcO4) for the targeted parotid gland in the following circumstance: A (99m)TcO4 scintiscan will only be performed and used to determine eligibility if the isotope is available. If the isotope is not available, this inclusion criterion is not applicable. 6. Abnormal sialogram (an altered ductal network with sialectasis) for the targeted parotid gland. 7. No current evidence of malignancy by otolaryngology assessment, including a clinical history, nasopharyngolaryngoscopy, and negative CT or PET scan (e.g. reference 58). 8. Absence of shedding wild type adenovirus in the saliva sample collected from the targeted gland at the pre-dose visit 1. Specifically, an aliquot of the pre-dose visit 1 saliva sample from the target parotid gland will be used to infect A549 cells to test for the presence of shedding WT Ad virus. If infectious virus emerges during the subsequent 7-10 day follow-up period, then the participant will no longer be eligible for treatment and will be withdrawn from the study. However, if no cytopathic effects are observed over a 7-10 day period, the participant may be treated provided all other eligibility criteria are met. If stimulated saliva cannot be collected at the pre-dose visit 1, this inclusion criterion is not applicable. 9. Must be disease-free for at least 5 years, with the disease-free interval calculated from date of last cancer treatment (i.e., date of last radiation, chemotherapy or surgery) to date of pre-dose visit 1. 10. Willingness to practice the required birth control method ("barrier" contraception, i.e., condoms, diaphragm) until AdhAQP1 is no longer detectable in their serum or saliva. Women who cannot bear children (post menopausal or due to a surgical intervention) also will be required to practice barrier birth control methods until AdhAQP1 is no longer detectable in their serum or saliva. 11. Able to stay at the NIH hospital for the period of time necessary to complete each on-site phase of the protocol. 12. No history of allergies to any medications or agents to be used in this protocol. 13. On stable doses of medications (greater than or equal to 2 months from the pre-dose visit 1) for any underlying medical conditions. EXCLUSION CRITERIA: 1. Pregnant or lactating women. Women of childbearing potential are required to have a negative serum pregnancy test at pre-dose visit 1 and a negative urine pregnancy test within 24 hours of treatment. 2. Any experimental therapy within 3 months of planned AdhAQP1 administration (Day 1). 3. Any active respiratory tract infection in the 3 weeks prior to planned AdhAQP1 administration (Day 1). 4. Active infection that requires the use of intravenous antibiotics and does not resolve at least 1 week before planned AdhAQP1 administration (Day 1). 5. Evidence of active substance or alcohol abuse or history of substance or alcohol abuse within two years of pre-dose visit 1. 6. Uncontrolled ischemic heart disease: unstable angina, evidence of active ischemic heart disease on ECG, congestive heart failure (left ventricular ejection fraction \< 45% on MUGA or echo) or cardiomyopathy. 7. Asthma or chronic obstructive pulmonary disease requiring regular inhaled or systemic corticosteroids. 8. Individuals taking prescription medications (anti-cholinergics, anti-depressants) likely to result in salivary hypofunction. 9. Individuals with a history of autoimmune diseases affecting salivary glands, including Sj(SqrRoot)(Delta)gren s syndrome, lupus, scleroderma, type 1 diabetes, sarcoidosis, amyloidosis, and chronic graft versus host disease. 10. Use of systemic immunosuppressive medications, e.g., corticosteroids. Topical corticosteroids are allowed. 11. History of a second malignancy, within the past 3 years, with the exception of adequately treated basal cell or squamous cell carcinoma of the skin or in situ carcinoma of the cervix. 12. Active hepatitis B, hepatitis C or HIV infection tested using blood collected at pre-dose visit 1. 13. WBC \<3000/microL or ANC \<1500/microL or Hgb \<10.0 g/dL or platelets \<100,000/microL or absolute lymphocyte count less than or equal to 500/microL using blood collected at pre-dose visit 2. 14. ALT and/or AST \> 1.5 times the upper limit of normal (ULN) or alkaline phosphatase \>1.5 times ULN using blood collected at pre-dose visit 2. 15. Serum creatinine \> 2 mg/dL using blood collected at pre-dose visit 2. 16. Individuals who are active smokers. 17. Individuals who consume more than one alcoholic beverage/day. 18. Individuals who have an allergy to iodine or shellfish and thus are unable to have sialographic evaluations. 19. Individuals whose targeted parotid duct is not clinically accessible on screening sialography evaluations. 20. Individuals who on sialography have a distal stenosis in the targeted parotid gland that would impede vector delivery. 21. Individuals who likely would require use of a general anesthetic for ultrasound- guided core needle biopsy (applicable only for participants in dose cohorts 2-5). 22. Significant concurrent or recently diagnosed (\<2 months from Day 1) medical condition that, in the opinion of the Medically Responsible Investigator, could affect the participant's ability to tolerate or complete the study. 23. Live vaccines within 4 weeks of first infusion. 24. Previous participation in a rAd5 vector gene transfer study.