The aim of this paper is to investigate the implementation of genres, pertaining to non-fiction, in four different universal classification schemes BC2, UDC, DDC, SAB. It is not the aim of this paper to answer the question why certain genres are more implemented than others, or vice versa. Instead it is intended to be an investigation into the concept of non-fiction genres with the aim of attracting attention to the many interesting aspects of this concept for library- and information science research. An analysis of the schemes general auxiliary tables is performed by comparison with a specific genre-system devised by Ottar Grepstad. This genre-system is organised by dividing different genres into groups according to linguistic criteria. The analysis gives us a characterisation of the individual schemes, and it also gives us, in a comparison of all of the schemes, an idea of which specific genres and types of genres that are the most general, or the most ignored ones. The results of the analysis show that genres of two specific types dominate in all of the schemes. Of these two the guiding type of genre is the most frequent one, consisting of such genres as handbooks, manuals, guides, dictionaries and encyclopaedias. The argumentative and investigative type of genre was also found to be dominating. Frequent examples of this type of genre were genres pertaining to scientific work such as theses and reports. The other types of genres could only be found to a much lesser extent, with the exception of some genres of the educational type. Narrative and descriptive types of genres were not implemented to any greater extent, and most genres within these types were not implemented at all.