In the last years the University of the Basque Country EHU, like most European Universities, has increased the offer of English Medium Instruction (EMI). However, as this is a relatively new situation we do not have much research analysing this matter and shedding light on the impact this may have on different aspects of the learning-teaching process. In this study, we compared EMI and BMI (Basque Medium Instruction) lessons from the faculty of Economics and Business focusing our attention on classroom interaction. The aim of the study was to examine whether the Medium of Instruction (MOI) and the teacher lecturing may affect students’ oral participation. Results revealed that the MOI did not seem to be a relevant factor when it came to interaction, as no significant differences were observed when comparing EMI and BMI lessons. These results were in line with previous studies (Ngussa, Citation2017; Serna-Bermejo & Lasagabaster, Citation2023). Nevertheless, teachers’ teaching style turned out to be a relevant aspect since it affected classroom interaction significantly. These findings are also in line with former research (Sánchez-García, Citation2016; Serna-Bermejo & Lasagabaster, Citation2023).