This study aims to explore the perceptions of university students and instructors regarding English as the medium of instruction for teaching science courses in the United Arab Emirates (UAE). One hundred English as a Foreign Language students from several science courses participated in the current study. They completed a self-assessment questionnaire about the impact of EMI course-taking experiences on their English academic skills. In addition, semi-structured, individual interviews were conducted with ten students and four instructors in science classes using EMI. A mixed methods approach was employed to analyze the quantitative and qualitative data generated. The study revealed that the impact of EMI on the students' learning experiences is due to their varied educational and linguistic backgrounds. Most of the students and half of the instructors advocated English-only science instruction. This study provides suggestions for EMI to develop further at the university in the study, and in the UAE region.