Influenza causes annual worldwide epidemics of respiratory disease. Currently, the United States and many other countries recommend influenza vaccination for persons who are at high risk for influenza-related complications. This commentary explores the potential benefits of a policy advocating universal annual influenza vaccination and outlines obstacles that need to be overcome to make such a recommendation feasible. The 5-year experience of a free influenza vaccination program for everyone > or =6 months of age in the Canadian province of Ontario is reviewed.