Most graduate schools require students to take an entrance exam as part of the application. The GRE and GMAT are considered good predictors of an individual’s performance in graduate school, and many admissions committees weigh these scores heavily when making their decisions. In 2016, 584,677 people took the GRE (ETS 2016) and 261,248 people took the GMAT (Chan & Svancer 2016).
In the past, the GMAT was required for business school, much like the MCAT is required for medical school and the LSAT is required for law school admissions. The GRE General Test was required for most other graduate programs in the arts and sciences.
Recently, many business schools have begun to accept the GRE or GMAT, giving students the freedom to choose which test to take. If you are planning to apply to business school in addition to other graduate programs (such as economics or political science, for example), or if you are interested in a joint-degree program, it might make more sense to take the GRE (especially if you would only have to study for and take one exam).
On the other hand, if you are really only interested in attending business school, it might be better to take the GMAT, because that sends a clear signal to admissions committees that you are committed to getting an MBA. Many schools claim that they have no preference – if that is the case for your desired school, you should take the test on which you think you will score the highest.