[Public health: an interdisciplinary challenge].

Presented as an opening lecture of the new postgraduate education programme of both the Technical and the Free University of Berlin, sponsored by the German Federal Minister of Research and Technology, this lecture recalls the foundation of the first School of Public Health (The Johns Hopkins School of Hygiene and Public Health, Baltimore, Md., USA) by William Henry Welch, 75 years ago. Already in this early experience, several central topics of Public Health can be traced back: for instance the exact description of health problems of total population groups, the aetiological understanding of health problems as well as the transfer of knowledge in public health programmes. After a definition of the Public Health concept both in- and outside Germany, the article reviews three examples of core topics of Public Health. Drawing on results from the first report "Health of Zurich", applications of descriptive epidemiology for both priority finding in Public Health as well as aetiological research are illustrated. The second example, with data from a recent representative survey of adults swiss germans on the issue of discrimination against persons infected with HIV draws attention to the central importance of social sciences within Public Health. Finally, the third example discusses recent advances in health services research, including issues of health economics, an other important part of an interdisciplinary Public Health understanding.