Summary The antibody responses of hospital staff volunteers to polyvalent influenza vaccines containing either intact virus or SPEE virus antigens were compared. Significant increases in HI antibody against each virus strain in both vaccines were observed. Furthermore, postvaccination antibody titers against three of the four strains were significantly greater in the group receiving the SPEE antigens than were those in the group given intact virus. Evidence that the SPEE antigens may be more efficient antibody stimulators than their intact counterparts is presented and discussed.