The application of registers in the context of an archival source for scientific research is most often found in the research work of historians, mainly in its auxiliary sciences of genealogy and historical demography. However, although the mentioned source is most often in the service of the said sciences, they represent not only the corpus for historical research, but also for research of everyday life (ethnology), palaeography, linguistics if it is about old registers written in old forms and types of letters, etc. Thus, their role is found in a much wider range of scientific disciplines. Moreover, registries in the contemporary world are not used exclusively in the segment of traditional humanities, but their application is in a certain part of digital humanities, a fastgrowing interdisciplinary field that is emerging as a kind of response to the already established technological revolution. In this way researchers of history, demography, ethnology, linguistics ... are faced with challenges expressed in a new, changed methodology and approach to research, where the ‘craft’ of these researchers provides a different approach to information, and data analysis revolutionary and innovative results that again open an unlimited questions to science. In addition to the theoretical analysis of the importance and application of registry books in science, with a special emphasis on digital humanities, the research part of the paper focused on surveying archives and interviewing scientists in the field of humanities, provides answers to questions such as: how important are the registry books and what is their usability? What do registries represent in the academic community and how are they useful in their work? How much attention is paid to them in terms of protection and preservation? Are there any plans for their complete digitalization, etc.? Considering the fact that the topic of this paper is complex and covers a wide field of research, in the analysis this paper is limited to the territory of the Republic of Croatia and presents data related exclusively to its geographical area.