The present study systematically reviewed research that was conducted to analyze the errors within the written expressions of individuals learning Turkish as a foreign language. The sample of the study consisted of 16 articles that were identified through the review of literature. The articles that focused on the written expression errors made by learners of Turkish as a foreign language, published between 2010 and 2019, and written in Turkish with the participation of adult learners of Turkish as a foreign language were included in the study. The findings of the articles were assessed using content analysis to organize the systematic review. The results of the systematic review indicated that the errors that were most frequently made by foreign students in writing were related to spelling and punctuation (40%), followed by grammatical errors (34%). While lexical errors constituted 14% of errors, syntactic errors constituted 12% of the errors. At all levels, lexical and syntax errors were fewer than other types of error.