This study aims at investigating the lexical errors and their effects on the written performance of Saudi EFL university students of College of Science & Arts, Tanumah at King Khalid University in the second semester of the academic year 2019/2020. Moreover, the study aims at identifying and analyzing the lexical errors, determining the causes of these errors, and suggesting suitable solutions to these errors. The population of this study covers both all English language teaching staff and third level EFL university students in the above-mentioned college. The analytical descriptive approach is adopted to handle out this study. The study employs an error classification of six categories of lexical errors including errors of word choice, errors of literal translation, errors of paraphrasing, errors of distortions and errors of word formation .Testing and unstructured interview are used as tools for collecting data. The findings of the study indicate that the students commit lexical errors in their essay writing due to some factors such as interference of mother tongue and inadequate vocabulary knowledge and other factors. The study recommends, for example, that EFL university instructors should encourage students to increase their stock of vocabulary by providing them with reading materials on different topics and through exposure to words in contexts, and not only concentrate on introducing new words with their meaning in isolation. They are also recommended to give immediate feedback to students about the words usage during classroom activities.
Keywords: EFL university students, Error Analysis, Essay Writing, Lexical errors
