Abstract:
English is an essential international language that Thai students have been learning since kindergarten. Nevertheless, even university students still have troubles using English correctly and fluently. These troubles include listening, speaking, reading, and writing skills. This research aims to examine problems of Thai undergraduate students in using English by focusing on academic writing. Data was collected through a questionnaire from 250 Thai undergraduate students and through a writing test from the same group for 50 persons. The results revealed that the most important obstacle of using English is a writing skill, followed by speaking, listening, and reading skills. The essential factor causing the writing problem is the lack of using English in daily life. Furthermore, the writing test expressed students’ problems of sentence structures, grammar, limited vocabularies, and paragraph structure. Increasing English writing courses and using more English in daily life can be ways to improve the students’ English skills.