Ethical issues about nosocomial infections have to be considered in two fields: the daily practice and the doctors participation in the institutional or suprainstitutional committees, involved in various administrative, strategic or financial measures aiming at the control and the prevention of nosocomial infections. In daily practice the ethical rules are founded on the principles of individual good: regarding nosocomial infection the principle of non maleficence is the most relevant. Physicians, nurses or other health professional may have a part of responsibility in a nosocomial infection. However there are many impediments to their acknowledgement of their own moral responsibility. The most important impediments may be: a) the more and more collective approach of care in many hospitals wards; b) the fact that the consequences of a nosocomial infection in one patient can extend to patients in other structures and, thus, can remain ignored by those who are responsible for this infection; c) paradoxically enough, the high attention paid to the theoretical issues concerning nosocomial infection. It must be kept in mind, too, that the ethical issues concerning nosocomial infections include the necessity for providing the patients with adequate and truthful information about the risks of nosocomial infection, in every hospital or ward, and--if it happens--about the nosocomial nature of an infectious complication. There is also some concern about the fact that the various modalities of legal responsibility and indemnification for a nosocomial infection, that the law has already specified or could define in a near future, may have a negative influence on the capacity of many care providers to keep a feeling of their moral responsibility. In the official committees devoted to decide administrative, strategic or financial measures able to help scientific research and to induce better practice in the surveillance and the prevention of nosocomial infections, the ethical principles at use are not only those of good but also those of justice. The balance between these ethical principles is delicate, however, for doctors, the main concern should be to avoid any distortion of the debate which could result from their confusing use of the principles of good.