SINCE the efficacy of influenza virus vaccine was first established, in 1944, this agent has been used extensively by the United States Army in mass immunization programs. In spite of the fact that serious allergic and toxic reactions to the vaccine are known to occur,* in actual practice these have been rarely encountered. Therefore, a recently observed patient, who exhibited a reaction to the vaccine which was both unusually severe and of a singularly ominous type, seems worthy of reporting. REPORT OF CASE A 19-year-old white enlisted man was admitted to the Communicable Disease Section of an Army General Hospital on Nov. 23, 1953, in a semicomatose state. He had been entirely well until the day of admission, when in the morning he received an injection of influenza virus vaccine. He had no symptoms following this until 2: 30 p. m., when there was a sudden onset of profuse rhinorrhea