This paper discusses the moral justification for using personal data without informed consent, from both medical records and biological materials, in research where subjects are not physically present in the study and will never have any contact with the study investigators. Although the idea of waiving the requirement for informed consent in certain investigations has been mentioned in several ethical guidelines formulated by epidemiologists and physicians since the late 1980s, these guidelines are now of limited use due to legal restrictions on the use of personal data in most western countries. Several misconceptions that form the basis for legal restriction of health research are discussed: lack of knowledge of the need to link personal information from health services with personal information produced outside the health system in many biomedical investigations; the assumption of a deterministic model of disease causation in which the prediction of disease occurrence is based on a genetic association despite the fact that most genotypes for common diseases are incompletely penetrant; the lack of a logical rationale for the recommendation in the Declaration of Helsinki that only research that offers some benefit to study subjects is justified; the great lack of knowledge about research methodology revealed in some alternatives proposed to avoid using personal data; and the lack of a debate about the ethical double standard of institutions and investigators in countries that prohibit the use of personal data but finance and carry out studies in other countries where it is permitted.