Ten peanut-sensitive patients were enrolled in a double-blind crossover trial to determine whether ingestion of peanut oil can induce adverse reactions in such individuals. All patients had experienced prior allergic reactions to peanut ingestion, including any of the following: generalized urticaria, angioedema, abdominal cramps, vomiting, diarrhea, bronchospasm, or shock. All patients had elevated levels of serum IgE antibodies to both crude peanut extract and the purified peanut allergen, Peanut-I, by RAST assay; binding values ranged from 2 to 26 times that of negative control serum. All patients demonstrated negative puncture skin tests to both peanut oil and olive oil (control). At 30-min intervals, patients ingested 1, 2, and 5 ml of either oil contained in 1 ml capsules while under constant observation. These quantities exceed the maximum estimated dose of peanut oil that would occur in single meals. Patients returned 2 wk later for ingestion challenge with the remaining oil. No untoward reactions were observed with either peanut oil or olive oil. Peanut oil ingestion does not pose a risk to peanut-sensitive individuals.