Housworth, J. (Bureau of Epidemiology. Center for Disease Control, Atlanta. Georgia 30333) and A. D. Langmuir. Excess mortality from epidemic influenza. 1957–1966. Am J Epidemiol 100: 40–48. 1974.—A study of excess mortality in the United States from 1957 through 1966 revealed seven epidemic periods associated with the prevalence of influenza A2 or B or both infections, and one period in July 1966 associated with a heat wave. More than half of the excess deaths are attributed to diseases of the heart, or the circulatory or nervous systems. The proportion ascribed to respiratory causes varies from 38% in severe epidemics of influenza A2 to as low as 22% during mild epidemics of influenza B. Severe epidemics of influenza result in small but significant excess mortality attributed to tuberculosis, asthma, chronic rheumatic heart disease, diabetes, and neoplasms. Maternal deaths showed no excess mortality during influenza epidemics. Similarly, infant mortality was not influenced to a measurable degree by influenza epidemics.