To characterize risk factors for outbreak-associated influenza illness and death in a nursing home. Outbreak investigation with predetermined and concurrently determined risk information. A nursing home service in a multiward chronic care hospital, Honolulu, Oahu, 1989 to 1990. Elderly nursing home patients receiving long-term care. Influenza vaccination, amantadine administration, and infection control measures. Neither routine infection control measures nor vaccination prevented illness, complications, or death in a nursing home outbreak of influenza A. The 55% case-fatality rate resulted from severe pneumonia. Influenza transmission may have been mediated by staff via either contaminated hands or fomites. Data from this and other outbreaks suggest that recommendations for preventing nosocomial influenza in the nation's 1.5 million nursing home residents should be reconsidered.