Public Health Service (PHS) needs an epidemiological approach to execute and implement its widespread tasks, as laid down by law. Data collection and transfer is strictly limited by law; PHS has usually to refer to its own (current) data, collected and used primarily for individual applications and therefore of limited epidemiologic use. The legal basis for epidemiologic work in the field of PHS is interpreted, the restrictions by data protection are shown, the limited use of the present current data basis is discussed. Finally, the role of PHS as part of the local administration is justified as well as its importance for community based health reports and health planning.