Medical audit in infection control today is accepted as an important element in the quality assurance of health care. In contrast, environmental auditing, which was approved in 1993 by the Council of the European Communities for industry ("Eco-Management and Audit Scheme-EMAS), has not so far been used as a tool to control and reduce environmental pollution caused by medical care in hospitals. The aim of this study was to investigate, whether environmental auditing in hospitals is useful. This process should also be cost effective. In this paper, methodological and organizational issues are described. Initially an environmental review of activities at the University Hospital, Freiburg and an eco-analysis of the input and output were performed. The first results of the study and a critical discussion will be presented in another paper.