This study aims to explore power asymmetry in the organisation of teacher-student interaction by looking at turn-taking systems and the restriction of participants. This is achieved by combining the frameworks institutional discourse, conversation analysis (CA) and critical discourse analysis (CDA) and by looking at sequences of teacher-student interactions at seminars. The study encompasses analyses of classroom discourse at university level and uses data culled from the Michigan Corpus of Academic Spoken English, MICASE. These data are analysed in relation to turn-taking systems and power asymmetry (i) to explore how teachers organise their classroom talk in terms of the allocation of turns, sanctions and control over the discourse and (ii) to determine to what extent teacher-student interactions show signs of power asymmetry. The results show that the teachers control the classroom discourse in a number of ways. Firstly, the analysis shows that the participatory roles of “teacher” and “student” have different claims to power and that these roles are more or less restricted by the design of the turn-taking system in place. Secondly, the teachers are found to organise the discourse in turn-taking systems that have implicit rules. Thirdly, the teachers not only have greater participation rights, but also greater control over the students’ participation rights, as witnessed by the fact that the students get disciplined if they break the rules of the system.