Described is an 11-year-old girl who had a reaction including urticaria and asthma to influenza immunization. The urticaria lasted for nine days. This patient had no clinical sensitivity to egg and no skin test reactivity to egg, but she did show positive skin test reactions to influenza B and bivalent flu vaccine. Since passive transfer did not produce positive skin tests, it would appear that the reactions were not IgE-mediated. The patient has not had subsequent urticaria. The possibility exists of reactions to influenza virus antigens or bacterial or other contaminants of the vaccine. More complete and detailed information about "contaminants" in influenza (and other egg embryo) vaccines should be made available so that these factors can be taken into consideration in seeking the cause of reactions to these vaccines and in possibly preventing reactions.