 Influenza is a common respiratory infection caused by several related viruses. Epidemics of influenza occur each winter and are responsible for an average of about 36,000 deaths each year in the United States. Most of these deaths occur among elderly persons and among people of all ages who suffer from chronic diseases, particularly of the lungs and the heart. Current influenza virus vaccines protect elderly persons against influenza, but not as well as desired. One consideration for trying to increase protection is to increase the vaccine dose, but there is some concern that increasing the dose may increase reactions to the vaccine such as sore arm, aches, or fever. One of the vaccine manufacturers has prepared an experimental influenza virus vaccine with a dose that is higher than the currently used dose. A previous study with the same high dose of the vaccine showed that it was well tolerated with only increased reactions at the injection site compared to the usual vaccine. Since the study, the high-dose vaccine has also been made without preservative thimerosal and gelatin, which are in the standard vaccine. It is expected that this vaccine can be given with little reaction, but this needs to be determined. It also needs to be shown whether such a vaccine stimulates higher levels of infection-fighting proteins or antibodies in the blood than standard doses of influenza vaccine. The purpose of this research is to compare reactions and antibody responses following standard flu vaccine to those following the experimental vaccine. Up to 410 people ages 65 years and older will be recruited from the community and from existing volunteer populations. Participants will receive either the high or standard dose injected in the muscle, remain in the clinic for 20 minutes afterward, and maintain a daily memory aid for 7 days. The memory aid will be reviewed by telephone 8-12 days after the injection and return to the clinic or contacted by telephone 6 months after the injection. This study is linked to DMID protocol 05-0028. 