In Japan, the concern about ethical issues in preventive medicine, especially in epidemiological investigation, has been gradually increasing in recent years. In this paper I introduce the following four topics : 1. privacy protection and the computer, 2. informed consent and publication, 3. the attitudes toward ethics among epidemiologists, 4. the attitudes toward epidemiological investigation among examinees. In my opinion, Japanese epidemiologists should give more attention to general ethical principles (Respect for persons, Beneficence) and to the practical methods to apply them in their research works. J Epidemiol, 1996 ; 6 : S137-Sl39.