Discussion forums provide students with accessible platforms for group discussions in e-learning environments. They also help lecturers to track and check student discussions. To improve student learning, it is important for lecturers to identify students' cognitive engagement in discussion forums. Therefore, this study aims to investigate students' cognitive engagement in e-learning through content analysis of forum posts. A total of 267 forum posts created by students during one semester were collected for analysis. Inferential statistics were applied to explore the relationship between students' cognitive engagement and their gender and the number of posts in forums. The results revealed that about half of the students gave their posts without any explanations, which reflected a low level of cognitive engagement. A large number of posts made little contribution to a high level of cognitive engagement. The results also showed no relationship between gender and the level of cognitive engagement. The limitations and implications of this study are also discussed.