During 1974 there was an apparent decrease in the reported amount of acute respiratory illness in the Navy and Marine Corps. Streptococcal infections continued to be controlled by the selective use of prophylactic benzathine penicillin in recruit training centers. Influenza immunization limited the impact of that illness, and serogroup C polysaccharide vaccine reduced the amount of meningococcal disease among recruits. Although some of the data are contradictory there are indications that fully potent live adenovirus vaccines lessen the frequency and severity of respiratory illness in recruit populations. Continued epidemiologic study will be required to fill the gaps in our knowledge.