Bilingual practices in university science courses are on the rise because of the internationalization of higher education. However, little is known about bilingual science teaching practices (BTP) of professors and their beliefs about this type of practice. In this exploratory study, a questionnaire was designed, adapted and applied to explore the BTPs of professors and their espoused beliefs about bilingual practices in university science courses in a Colombian university. The participants were 20 science professors who were asked to complete a twenty eight-item questionnaire. Findings indicate that a high number of participants espoused positive beliefs about the key role of bilingualism and English in undergraduate courses in the construction of an international academic view of science. Nevertheless, their BTPs were limited and they did not take advantage of bilingualism to enrich undergraduates' conceptual knowledge, bilingual repertoires, and scientific skills. Outcomes highlight the need to help professors understand the potential of bilingualism as a resource in the science classroom. This study also suggests that bilingual science professors' practices and beliefs should be considered as crucial elements in the building of research-based policies aimed at legitimating bilingual practices in university science courses.