This is a 38-week, randomized, double-blind, placebo-controlled, parallel group trial of approximately 150 patients who have a history of immediate hypersensitivity reaction to peanut protein.

Inclusion Criteria:

• The patient has a diagnosis of acute peanut allergy
• The patient meets the Xolair dosing table eligibility criteria by having a serum baseline IgE level between 30 and 1300IU/mL, and a body weight between 20 and 150 kilograms
• The patient is six to 75 years of age
• The patient reacts to peanut flour but not wheat (placebo) flour during the first Oral Food Challenge (OFC)
• The patient has a positive skin prick test to peanut or detectable serum peanut-specific IgE level
• The patient is able to swallow capsules

Exclusion Criteria:

• Have FEV1 value <80% predicted or any clinical features of moderate persistent asthma, as defined by the NHLBI guidelines
• Have other significant medical conditions (e.g., liver, gastrointestinal, kidney, cardiovascular, pulmonary disease, or blood disorders), which, in the opinion of the Investigator, make the subject unsuitable for induction of food reactions
• Have a history of allergy to wheat protein
• Have previously been exposed to monoclonal antibody treatment