This study aims to identify foreign-origin words found in reading texts in secondary school Turkish textbooks. The study was conducted in a qualitative research design and the research object is Turkish textbooks prepared by the Ministry of National Education Publications for the 5th, 6th, 7th, and 8th grades of secondary school. A total of 95 reading texts found in these textbooks were evaluated within the scope of the research. The texts were analyzed using the document analysis technique. According to the findings obtained from the reading texts, there are a total of 1995 foreign-origin words (604 different) from 12 languages in the 5th Grade Turkish Textbook; 2537 foreign-origin words (725 different), from 13 languages in the 6th Grade Turkish Textbook; 2851 foreign-origin words (645 different), from 11 languages in the 7th Grade Turkish Textbook; and 2809 foreign-origin words (731 different) from 10 languages in the 8th Grade Turkish Textbook. In all of the books included in the study, it was determined that there were a total of 10192 loanwords, 1565 of which are different, from 15 different languages. The most frequently used origin language of the words were detected as Arabic (57,91%), Persian (25,07%) and French (10,41%), and the most frequently used foreign-origin words were found as ve (f=625), her (f=168), zaman (f=156), insan (f=144), ki (f=143), ama (f=139), sey (f=122), kadar (f=110), saat (f=109), hiç (f=101), ya (f=98), kitap (f=89), adam (f=87), dünya (f=82), efendi (f=81), hep (f=72), bisiklet (f=70), köy (f=70), can (f=65), hâl (f=61), hemen (f=59), renk (f=59), hasta (f=56), kahve (f=55), ebru (f=54), dost (f=50), hareket (f=50) and hem (f=50), respectively. [Note: The publication year (2022) shown on the PDF is incorrect. The correct publication year for this article is 2023.]