The research investigates the use of complex sentences in students’ essay writing, exploring pedagogical implications for teachers to enhance students’ writing proficiency. 212 essays were collected from English-majored students in the last semester for essay learning at Can Tho University, but only 162 essays were qualified for analysis, equivalent to the number of essays in the corpus by Truong & Do (2021). Their complex sentence structures were analyzed and compared with the corpus to identify similarities and differences in the use of complex sentence structures. The findings of this research suggest that there are clear patterns in the types and frequency of complex sentences used by students, which may have implications for the design of the curriculum as well as the teaching and learning of writing essays. Implications for classroom practice and future research directions are discussed.