Three patients are presented who ingested a health food known as "bee pollen" and who experienced an immediate allergic reaction. Examination revealed that the bee pollen contained dandelion pollen, which belongs to the Compositae family as does ragweed. In vivo and in vitro studies demonstrated that the patients were sensitive to several Compositae family members, rather than to insect-derived antigens. In addition, radioallergosorbent inhibition studies confirmed the suspected cross-reactivity between the health food and Compositae pollens. This study indicates that atopic individuals may experience anaphylaxis from ingestion of antigens in certain food stuffs that cross-react with pollens to which they are sensitive.