This study is focused on the subject representation based on a reflective perspective in terms of ethics in the field. It aims to analyze the professional perception of Brazilian university librarians about ethics in subject representation. It is a descriptive study of a quantitative nature that usesthe application of online survey, which was applied to professionals in charge of managing the technical processing section of university libraries located in federal public universities in Brazil. The results demonstrate that ethics is well assimilated by technical processingmanagers, even though they face interpretive dilemmas as well as a major concern about indexing process and its embodiment via term. Despite every care in the equal treatment of the different issues, reported by the respondents, inconsistent substitutes are still echoing in the information retrieval system, making it necessary to seek training and unrestricted use of documentary instruments in order to avoid biased interpretations and representations. Simultaneously, qualification, collaboration and participation of the user are understood as a way of supporting the ethical instance of the subject representation, as well as the need for further evolution of the library literature within thisperspective. It is concluded that the ethical dimension in the subject representation is understood by Brazilian university librarians who can identify impasses, difficulties, problems, solutions and needs for greater assertiveness in this context.