This study examines the impact of German orthographic rules on the written Turkish of Turkish-origin students receiving education in Germany. Using qualitative research methods, particularly content analysis, written texts of students aged 10-15 who receive education in German were analyzed. The study found that students are influenced by German linguistic structures in areas such as capitalization, word composition, sentence structure, verb conjugation, pronoun usage, and punctuation errors. The research results indicate that students unconsciously apply German grammar rules when constructing Turkish texts, leading to grammatical errors and coherence issues. One of the most common mistakes is the direct transfer of German word order and compound word structures into Turkish. The study provides recommendations for necessary adjustments in the education system to preserve and correctly utilize the mother tongue.