Studies have recently been published of surveys of antibodies to common respiratory viruses in human sera from several parts of the world. The present article reports the findings of a survey of antibodies to two more viruses (adenovirus type 8 and coxsackievirus type A21) in human sera mainly collected from six widely separated geographical regions (Alaska, England, Marshall Islands, Sarawak, South-West Africa and Tunisia).A world-wide geographical distribution of infection with these two viruses was found. However, antibodies to individual viruses were not found with the same frequency in all countries; and, in marked contrast to the findings in the earlier surveys of antibodies to the common respiratory viruses, the frequency of antibodies was not the same for each virus in sera from the same country. It was not possible to draw any final conclusions as to the reasons for the observed differences.