Inclusion Criteria:

- Study subjects with a histologic diagnosis of erythroplakia with dysplasia, severe
dysplasia, or carcinoma in-situ of the head and neck. Study subjects with carcinoma
in-situ will be eligible only in situations where standard therapy is not indicated.

- ECOG performance status of 0-2.

- Males and females 18 years of age or older.

- Study subjects capable of providing informed consent indicating an understanding of
the potential risks, benefits and complications of the proposed treatment.

- Premalignant lesions but where the final pathologic evaluation notes a suspicion or
the presence of focal microinvasion but where the predominant lesion is premalignant.

- Clinical assessment of the depth of the lesion which confirms that the lesion's
clinical depth is consistent with the pathologic evaluation that identifies the
suspicion or the presence of only focal microinvasion.

- Agreement with the treating surgeon that the suspicion or the presence of focal
microinvasion can be treated without surgical resection.

Exclusion Criteria:

- Study subjects in whom the targeted lesion/area has invasive squamous cell carcinoma
of the head and neck greater than 1.5 mm from the tissue surface.

- Study subjects with invasive squamous cell carcinoma of the head and neck.

- Study subjects who are pregnant or lactating.

- Study subjects who have a platelet count of less than 100,000/cubic mm.

- Study subjects who refuse to provide informed consent (see 3.4).

- Study subjects with elevated aspartate aminotransferase (AST), alanine
aminotransferase (ALT), alkaline phosphatase, or total bilirubin levels >2X normal or
a history of chronic liver disease or cirrhosis of the liver.

- Study subjects with a significant cardiovascular history such that an evaluation by a
cardiologist deems the study subject to be at risk with the hypotension that may
occur with oral administration of Levulan® .

- Study subjects with porphyria or hypersensitivity to porphyrins.

- Study subjects who have had an adverse reaction to ondansetron or lorazepam.

- Study subjects who have an abnormal baseline creatinine level or diagnosed kidney
disease.

- Study subjects who have a medical history of immune suppression. This will include
patients with a past transplantation requiring ongoing immunosuppressive medications
and also include subjects with HIV infection.