For years, universities worldwide have offered English-medium degrees as a way to attract international students and staff, enhance their institutional profile and promote multilingualism. In Europe and the European Higher Education Area (EHEA), English-medium instruction (EMI) is more recent, but the dimension and speed of its implementation has outpaced language policies, methodological considerations and empirical research. In view of this, this paper focuses on an empirical study examining the effect that the teaching of a Business Administration degree in English as a foreign language may have on Spanish students' academic performance (as measured through coursework and final grades), when compared to their counterparts' learning in Spanish. Students' grades are analysed in three different disciplinary subjects and treated statistically. Findings show that both cohorts obtain similar results, suggesting that the language of instruction does not seem to compromise students' learning of academic content. Differences, however, are found regarding learners' performance in the three disciplinary subjects under scrutiny, with history yielding slightly higher results than accounting and finance. This finding runs counter to the general belief that the more verbal subjects, like history, would have a "limiting" effect on EMI students' final performance and, moreover, raises questions concerning disciplinary differences and assessment.