This paper reports on a cross-disciplinary study of the rhetorical structure of Three Minute Thesis (3MT) presentations, an increasingly popular yet largely unexamined academic speech genre. The study analyzed a corpus of 142 presentations by PhD students from four disciplines chosen to operationalize two widely discussed disciplinary distinctions (i.e., hard vs. soft and pure vs. applied disciplines). The analysis identified eight distinct rhetorical moves in the 3MT presentations, including six obligatory moves (i.e., Orientation, Rationale, Purpose, Methods, Implication, and Termination) and two optional ones (i.e., Framework and Results). Further analyses revealed statistically significant associations between disciplinary affiliation and the likelihood to employ three moves (i.e., Framework, Methods, and Results). These relationships are explained in terms of the dominant epistemological codes at work in the different disciplines. The findings have important implications for graduate students, 3MT tutors, EAP instructors, and other academics involved in preparing PhD students for 3MT competitions and teaching spoken academic discourse in general.