Peanuts are a common cause of food allergy, but they have infrequently been documented as causing fatal anaphylactic reactions. We review five previously reported fatalities caused by peanut allergy, along with data on IgE binding proteins in extracts of a commercial product containing peanuts that have been deflavored and reflavored and colored to resemble walnuts, pecans, or almonds. Ingestion of this product may pose hazards to peanut-sensitive persons. Finally, we identify several factors that may contribute to the severity and possible lethality of food-induced anaphylaxis.