Cohesion plays an essential part in writing. This study aims to find out what grammatical cohesion device students used in writing. This study is qualitative. It was conducted during the semester. Fifteen university students who studied essay writing participated as participants in this study. The students’ writing drafts were collected and analyzed. Content analysis was applied. The results showed that the students use two grammatical cohesion devices in their essay writing; references and conjunction. References consist of personal references, demonstrative references, and comparative references while conjunction consists of additive conjunction, adversative conjunction, causal conjunction, and temporal conjunction. On the other hand, two grammatical devices that were not found in students writing drafts are substitution and Ellipsis devices. Thus, those two devices are mostly found in oral communication. It means that the analyzed passages do not expose all cohesion devices sufficiently and provide too many highlights on one type that is the reference. This fact showed that the sentences within the text should not be connected by the existence of all cohesion devices. Some of the adequate devices were as much as necessary to create a series of sentences called a text. Some presence of them is already enough to create cohesion.