The aim of this study is to examine how the nature of science dimensions are represented in the secondary school 5th, 6th, 7th, and 8th grade science textbooks of the last twenty years. It is also within the scope of the research to investigate how these dimensions in the textbooks changed during the twenty years. The document analysis method was used in order to qualitatively gather data for the research. The data sources in the study consist of a total of 62 textbooks which were allowed to be used in schools by the Ministry of National Education. Among the examined textbooks, only the textbooks published in 2020 were published by private publishing houses, and all other textbooks were published by the Ministry of National Education publishing houses. Textbooks were examined in terms of ten sub-dimensions, such as "empirical", "inferential", "creative", "theory-driven", "tentative", "myth of the scientific method", "scientific theories", "scientific laws", "social dimensions of science", and "social and cultural embeddedness of science", within the scope of the nature of science. The examination of the textbooks in terms of the representation of the specified sub-dimensions was carried out using the detailed rubric developed by Abd-El-Khalick, Waters, and Le (2008). As a result of the examination of science textbooks, "creative", "tentative", and "inferential" sub-dimensions were mostly represented, followed by "empirical", "theory-driven", and "social and cultural embeddedness of science". The sub-dimensions of "scientific theories", "scientific laws", "myth of the scientific method", and "social dimensions of science" are either very limited or not represented. However, in general, it has been concluded that all science books published in the last 20 years in each grade are inadequately represented in terms of the sub-dimensions of the nature of science. [For the complete volume, "Proceedings of International Conference on Studies in Education and Social Sciences (Antalya, Turkey, November 11-14, 2021). Volume 1," see ED625228.]