Language teaching aims to improve comprehension and narrating skills. While oral narration skills are mostly needed in daily life, writing becomes prominent in academic and cultural activities. In this study, the problems in written expressions of 16 students who are studying Turkish as a second language at Yıldız Technical University Turkish Teaching Centre A1 level and will start their bachelor, master and doctorate degrees. The data of the study is obtained from the texts written by the students in writing course. Those texts written by guided writing method have some topics such as introducing families, patient-doctor dialogue, travel plan, giving a recipe etc. The errors that are identified in writing activities have been analyzed according to error analyzing method. Initially, the detected errors have been defined, later they have been classified and mentioned with their frequency rates. According to the results, the students speaking Arabic, Persian, Bosnian and Lala as their mother tongue make more mistakes in writing while the students speaking Shona, Hausa and Malay as their mother tongue make more stylistic errors.