Inclusion Criteria:

• Males and females, aged 18 years and older.
• Patients must have histologically confirmed diagnosis of mild-moderate dysplasia or severe dysplasia/carcinoma in situ (CIS) of the oral cavity or oral pharynx.
• Patients must have clinical evidence of mild to moderate dysplasia or severe dysplasia/CIS of the oral cavity or oral pharynx that is diffuse.
• Patients must have diffuse* premalignant disease of the oral cavity or oral pharynx and must have: a) been previously treated with conventional treatment (e.g.: radiation or surgery) for a prior head & neck malignancy or b) failed biochemoprevention approaches for premalignant disease or c) failed other therapeutic approaches for premalignant disease. (*See protocol for definition of diffuse.)
• All patients must have a Karnofsky performance status of greater than or equal to 70% (Karnofsky scale, Appendix B).
• All patients must sign an informed consent indicating that they are aware of the investigational nature of this study in keeping with the policies of the institution.
• If female and of childbearing potential (non-childbearing defined as 1 year post menopause or surgically sterilized), patients must have a negative serum pregnancy test. Patients (male and female) must agree to use barrier contraception while on study and to avoid pregnancy for 1 year after treatment.
• Patients must have negative serology for the Human Immunodeficiency Virus (HIV) Type I. (Safety of the product has not been established or studied in immunosuppressed populations).
• Patients must have adequate bone marrow function (defined as peripheral absolute granulocyte count of greater than or equal to 2,000/ul and platelet count of greater than or equal to 100,000/ul), adequate liver function (bilirubin less than or equal to 1.0 mg/dl), and adequate renal function (creatinine less than or equal to 1.5 mg/dl).
• Patients must not knowingly be in contact with former tissue or organ transplant recipients and persons known to them to be suffering from severe immunodeficiency disease (either acquired or congenital) during treatment or within 28 days following the last dosing with Ad5CMV p53 (INGN 201).

Exclusion Criteria:

• Active squamous cell carcinoma of the head and neck.
• History of prior malignancies (excluding non-melanoma skin cancers and aerodigestive cancers) unless curatively treated and disease free for greater than or equal to 2 years.
• Prior experimental therapy oral, systemic, topical, or directly injected into the lesion selected for treatment in this study, or radiation directly involving the lesion selected in the last three (3) months.
• Chemotherapy within 21 days prior to study (42 days for mitomycin C and nitrosoureas).
• Pregnant or lactating females. (Transplacental transfer and excretion in breast milk have not been studied with this agent).
• Active systemic viral, bacterial, or fungal infections requiring treatment.
• Patients with serious concurrent illness of psychological, familial, sociological, geographical or other concomitant conditions which do not allow for adequate follow up and compliance with the study protocol.
• Concurrent use of other investigational agents.
• Prior use of any other investigational agent requires a washout period of 8 weeks.
• Any immunosuppressive therapy (including corticosteroids > 10 mg/day) of prednisone or the equivalent.
• Aspirin use in an average dose of >175 mg/d.
• Patients evaluated by Internal Medicine with a baseline blood pressure of > or equal to 140/90 and deemed hypertensive.