At present time, there is uncertainty regarding whether influenza-like illness in healthy adults is best managed by preventive efforts that use the trivalent influenza vaccine, administration of neuraminidase inhibitors at the onset of illness, or recommendation of supportive care alone at the onset of illness. We conducted a cost-effectiveness analysis that examined these 3 strategies for managing influenza-like illness. Vaccination with inactivated trivalent vaccine would save approximately 25 dollars per person while resulting in a net gain of approximately 3.2 quality-adjusted hours relative to providing treatment with the neuraminidase inhibitor oseltamivir. A quality-adjusted hour is a fraction of a quality-adjusted life-year, which is the equivalent of 1 year lived in perfect health. Treatment with oseltamivir was associated with an incremental cost-effectiveness of approximately 27,619 dollars per quality-adjusted life-year gained relative to providing supportive care. Vaccination is cost-saving relative to providing either treatment with oseltamivir or providing supportive care alone.