The objective of the research was to analyze some errors in translating thesis abstracts from Indonesian to English and vice versa. They were written by the students of some faculties at the Muslim Nusantara Al-Washliyah, Medan, such as the Faculty of Letters, FKIP (the Faculty of Teacher’s Training and Pedagogy), and others. The research used qualitative approach, , and the theory of Larson’s translation process concerning diction (choice of words), phrases, incomplete or dangling sentences, grammar, etc. The data were obtained from the texts found in the abstracts of even semester, 2019. The data were gathered, sorted out, and analyzed to be used as the samples which were gathered in the form of tables. The gathered data were then verified by adjusting them to the objective of the research. The research was focused on the texts of abstracts in the translation process and its products by conducting library research and descriptive qualitative analysis. The data themselves consisted of primary and secondary data. It was expected that the result of the research could be the reference for the students in translating their abstracts by, of course, consulting their seniors and professional translators. The result of the research showed that the most dominant errors in the students’ thesis abstracts was in grammar (62.8%) followed by style (24%).