Abstract We estimated annual numbers and rates of influenza-associated deaths and hospitalizations by age group in the United States using a Poisson regression model incorporating World Health Organization (WHO) viral surveillance data. Mortality data were obtained between 1976 and 2000 from the National Center for Health Statistics (NCHS); hospitalization data were obtained between 1979 and 2001 from the National Hospital Discharge Survey (NHDS). Weekly influenza isolates by type and subtype were obtained from the WHO collaborating laboratories for the 1976–1977 through 1999–2000 seasons. Our models estimated annual averages of 6796 underlying pneumonia and influenza deaths and 28,076 underlying respiratory and circulatory deaths. The models estimated annual averages of 88,479 primary pneumonia and influenza hospitalizations and 225,985 primary respiratory and circulatory hospitalizations. We found significant increases in the numbers of influenza-associated deaths and hospitalizations by year among persons aged ≥65 years due to the aging of the population, the predominance of A(H3N2) viruses during the late 1990s and the increasing length of the influenza season during the 1990s.