This paper examines importance marking in the academic lectures of various disciplines from a functional viewpoint. Using a corpus-driven and discourse analytic approach, it extracted the importance markers of this inquiry from the 160 English academic lectures of the BASE corpus, which are equally distributed in the four main academic disciplinary groups of arts and humanities, social studies, physical sciences, and life and medical sciences. First, it was perceived that in highlighting importance, the discipline the speaker lectures in does not make a difference. Second, it was perceived that, irrespective of discipline, marking importance involves (1) pointing up the lecture, (2) expressing attitudinal evaluation according to a hierarchy of importance, (3) stating which topics need extensive coverage, (4) revealing what is likely to appear in the assessment, and (5) establishing interaction with the audience. Finally, ‘life and medical sciences’ lecturers were found to involve the students in the lecture more frequently than the lecturers of other disciplinary groups.