Influenza and other respiratory infections, the most common cause of acute infectious disease in U.S adults, are also the leading cause of outpatient illness and a major cause of infectious disease hospitalization in U.S. military personnel. Although respiratory disease control is improved, epidemics continue to occur, and respiratory disease in military trainees continues to exceed that in U.S. civilian adults. Overall, Department of Defense utilization of the trivalent inactivated vaccine was much lower than anticipated during the 2004–2005 season. The slow start to the 2004–2005 influenza season resulted in a low demand for influenza immunization by the medically high-risk beneficiary population of the Department of Defense. Surveillance for influenza during the 2004–2005 season in U.S. Army Europe reached unprecedented heights, testing and confirming more cases than in any previous year.