The objective of this paper is to analyze errors in the use of noun clauses made by senior English major students at Van Hien University. Identifying and analyzing errors as well as finding out the causes of errors are crucial in foreign language learning. Learning from previous studies about errors analysis, this case study focuses on analyzing thirty academic essays in order to find out solutions to improve accuracy in language competence for learners. The results explains that errors concludes 35 omission errors (51%), 15 misformation errors (22%), 13 addition errors (19%), 6 misordering errors (8%). The error analysis contributes to raising awareness about the precise use of general English syntax and noun clauses in particular to improve learners' language ability