Studies about feedback in writing have been oriented towards research on the learning of L2, with emphasis in the analysis of corrective feedback, that is, the use of the code by the learners. Studies about feedback oriented towards the appropriation of a discourse genre in L1 are still scarce. In the university context, the writing of a thesis or dissertation is a challenging and complex process, that requires diverse instances of feedback. In this way students can achieve the text required, according to the expectations of the academic community they are in. The objective of this research is, precisely, to describe the written comments (2070) that 12 supervisor teachers provide to 3 consecutive drafts to their students. The study is in the context of a major research and was carried out in four pedagogy programs of two Chilean universities in Concepcion city. To examine what the teachers comment the following categories of corrective comments, comments oriented to genre and object were applied. To describe how the teachers comment the categories or mode and hedged comments were applied. The results show that participants provide feedback to different aspects of the thesis writing, with a special emphasis to the drafts adjustment to the characteristics the genre and use of language. The role teachers predominately assume in their comments is the one of expert who has the authority to correct, give orders or make judgements, and acting as conveyors of the thesis genre.