Purpose-While distribution channels of theses and dissertations have changed significantly in the digital age, they are generally still considered grey literature. This paper aims to argue the applicability of the concept of grey to electronic theses and dissertations (ETDs). Design/methodology/approach-The paper is presented as a debate between two contradictory opinions on the application of the grey literature concept to ETDs. Findings-The paper provides a definition of grey literature and then discusses its application to electronic dissertations and theses. In particular, it assesses the aspects of acquisition, quality, access and preservation. Some arguments highlight the "grey nature" of ETDs, such as the limited access via institutional and other repositories. Other arguments (e.g. the development of ETD infrastructures and the quality of ETDs) question this grey approach to ETDs. The paper concludes that "greyness" remains a challenge for ETDs, a problem waiting for solution on the way to open science through the application of the FAIR (findability, accessibility, interoperability reusability) principles. Research limitations implications-Library and information science (LIS) professionals and scientists should be careful about using the concept of grey literature. The debate will help academic librarians and LIS researchers to better understand the nature of grey literature and its coverage, here in the field of ETDs. Originality/value-Some definitions from the print age may not be applicable to the digital age. The contradictory character of the debate helps clarify the similitudes and differences of grey literature and ETDs and highlights the challenge of ETDs, in particular, their accessibility and findability.