The purpose of this study is to compare tense choices in writing research abstracts across different academic disciplines: Humanities & Social Sciences (HSS) and Natural Sciences & Technology (NST). Specifically, across the disciplines, it compares 1) tense distributions, 2) associations between tense choices and rhetorical functions, and 3) tense distributions in each of the rhetorical functions. One hundred research abstracts were randomly drawn from the Internet databases. Verb tenses and rhetorical functions of the main clauses in the abstracts were identified and the rhetorical functions were further classified as deictic functions and referential functions. Separate analyses were done for deictic functions and referential functions. The results showed that the conventions of tense choices were not different across HSS and NST. For example, tense distributions did not differ in both the disciplines in that the present tense was dominantly found the same for both. Deictic functions were not significantly associated with tense choices in both the disciplines and the tense distributions of each of the deictic functions did not differ across the disciplines. Referential functions, on the other hand, were significantly associated with tense choices in both the disciplines, and the tense distributions of each of the referential functions did not differ across the disciplines. Educational implications are also discussed about tense choices in writing abstracts.