Recent research on problem-based learning (PBL) has shown that students need support when dealing with conflicting ideas in PBL-tutorial discussions. In the present study, we examined tutor facilitation during tutorial discussions, and particularly how the facilitation helped students to collaboratively resolve conflicts on knowledge. The study involved four PBL-tutorial sessions that included altogether 33 first-year medical and dental students. The sessions were videotaped and analysed using qualitative interaction analysis. Our aim was to find out how the tutor interventions encouraged students to elaborate on conflicting ideas, and how the interventions differed between conflict and non-conflict situations. We also examined how the tutors intervened during conflicts about factual or conceptual knowledge. The tutorial discussions included 92 tutor intervention episodes and 43 conflict episodes. The tutors intervened during 24 of the conflict episodes and resolved 13 of these episodes. Generally, the tutors often intervened by confirming what the students had said or by giving explanations, but they rarely asked questions that would stimulate the elaboration of knowledge. During conflicts on knowledge the tutors gave more explanations, but did little to encourage the students to deal with conflicting ideas. The tutors more often resolved conflicts on factual knowledge than conceptual knowledge. The findings suggest that tutor training should focus on promoting tutors' understanding on when to give direct explanations, and when and how to encourage students to collaboratively elaborate on conflicting ideas.