Vaccine containing 4 influenza A, 2 influenza B, and 2 adenovirus strains, emulsified in mineral oil-arlacel adjuvant, was given to 2,303 men. A control solution was given to 2,256 men in the same military units. Antibody response to influenza A2 and adenovirus Type 7 was of a high order. No undesirable reactions to the vaccine were noted. Illnesses of hospitalized men were classified by results of appropriate serologic tests. Outbreaks of influenza A2 and adenovirus Type 7 occurred. In the control group there were 35 cases of influenza, 40 of adenovirus infections, and 3 of both influenza and adenovirus. In the vaccinated group there were 2 cases of influenza and 4 of adenovirus infection. Other respiratory diseases occurred with comparable frequency in vaccinated and control groups. The protection ratio for influenza A2 was approximately 94% and for adenovirus, 90%.