Annual influenza vaccination of the U.S. elderly population has been demonstrated as safe and effective in reducing the risks of illness, hospitalization, and death. The Medicare Current Beneficiary Survey (MCBS) has measured annual influenza vaccination rates since 1991; the latest data available are for the 2001-02 influenza season. Since 1996, self-reported reasons for not receiving influenza vaccine also have been measured. During 1991-2002, MCBS indicated a steady upward trend in vaccination coverage among Medicare beneficiaries, with the exception of the 2000-01 influenza season, when vaccine distribution was delayed. The most frequently cited reasons for not receiving influenza vaccine were 1) not knowing that influenza vaccination was needed and 2) concerns that vaccination might cause influenza or side effects. During the 2000-01 influenza season, vaccine shortage or unavailability was noted for the first time as an important reason for nonvaccination. Further efforts are needed to educate the elderly regarding the benefits of influenza vaccination and to address any concerns regarding the safety of the vaccine.