Inclusion Criteria:

1. Patients with severe peanut allergy, between the ages of 7-25 years, having a history of significant clinical symptoms within 1 hr of peanut ingestion.
2. Total IgE >50 kU/L but <2,0000 kU/L.
3. Sensitivity to peanut will be documented by a positive skin prick test result and RAST test to peanut, with 20 kU/L as a lower limit for eligibility.
4. Patients must also fail a double blind food challenge with peanut at a dose of 100 mg or less (after a cumulative dose of 186 mg), with minimal or no reactions to the placebo challenge.
5. All female subjects of childbearing potential will be required to provide a urine sample for pregnancy testing that must be negative one week before being allowed to participate in the study.
6. Subjects must be planning to remain in the study area during the trial.
7. Subjects and/or their parents must be trained on the proper use of the Epi-Pen to be allowed to enroll in the study.

Exclusion Criteria:

Due to the risk of serious systemic anaphylactic reactions to peanut in this study, we will exclude:

1. Patients with acute infections, autoimmune disease, severe cardiac disease, and those who are treated with beta-adrenergic antagonistic drugs (beta-blockers, which increase the risk of more serious symptoms of anaphylaxis).
2. Subjects having a history of severe anaphylaxis to peanut requiring intubation or admission to an ICU, frequent urticaria, or history consistent with poorly controlled persistent asthma.
3. Total IgE > 2,000 IU/mL.
4. Subjects with unstable angina, significant arrhythmia, uncontrolled hypertension, chronic sinusitis, or other chronic or immunological diseases that in the mind of the investigator might interfere with the evaluation or administration of the test drug or pose additional risk to the subject e.g. gastrointestinal or gastroesophageal disease, chronic infections, scleroderma, hepatic and gallbladder disease, chronic non-allergic pulmonary disease.
5. Subject with an FEV1 or PEF less than 80% predicted with or without controller medication (if able to perform the maneuver) at screening, the oral desensitization visit, or food challenge visit.
6. Subjects who have received an experimental drug in the last 30 days prior to admission into this study or who plan to use an experimental drug during the study, who are current users of oral, intramuscular, or intravenous corticosteroids, or tricyclic antidepressants, or who are using medication that could induce adverse gastrointestinal reactions during the study.
7. Subjects refusing to sign the EpiPen Training Form.
8. Pregnant or breast-feeding females.
9. Subjects with severe food associated eczema, dermatitis herpetiformis, eosinophilic esophagitis, eosinophilic enteritis, proctocolitis, food protein induced enterocolitis syndrome (FPIES) or other gastrointestinal diseases. These requirements are necessary to limit the study to patients with primarily IgE mediated peanut allergy, and to exclude patients with peanut sensitivity mediated by cellular/T cell (non-IgE mediated) mechanisms.