Even in present times and given the current state of medical science, an influenza pandemic may be expected to occur in addition to the usual annual epidemic of the disease. A pandemic is defined as a concentrated worldwide occurrence of a disease within a short period. Such a pandemic has been registered three times in this century. The influenza epidemic of 1918 to 1919 ("Spanish flu") killed 20 to 40 million people. A similar pandemic occurred in 1957 to 1958 (Hong Kong) and in 1968 (Asia). Although the current state of medicine is such that the high morbidity and mortality of 1918 is unlikely to recur, adequate preventive measures are warranted in health care as well as in social and political fields. In the event of such a pandemic, a large number of persons in Austria may be expected to be affected by the disease. In contrast to other countries, a detailed plan of prevention does not exist in Austria at the present time. A sudden influenza pandemic would give rise to a number of grave problems in the medical field (increase in mortality rates) as well as in social and political areas (maintaining the infrastructure of the country). In light of this fact it appears necessary to investigate the possibility of an influenza pandemic and to take suitable precautionary measures.