The new undergraduate medical curriculum in Manchester uses problem-based learning (PBL) throughout the course. However, the major difference from other PBL schools is that in years 3 & 4 (phase 2) the students can use clinical experience when discussing the paper cases. The process is then developed further in year 5 (phase 3), in which there are no set PBL 'triggers' and students bring their own cases to the groups for discussion. In this study, we have explored what happens in the phase 3 (year 5) group sessions and how the students view them. A questionnaire and focus groups were used to generate data, from which a model was developed of what happens in a 'good' group session. The data suggest that most groups run on a case-presentation and discussion format, most commonly about clinical management and diagnosis. Students want tutors to act as an expert resource and to be flexible in allowing students to direct the discussions. University guidance about the group sessions was not generally used.