The aim of this study is to explore student's perceptions of incidents in tutorial groups and their perceptions of the tutor's role in these incidents. This study investigated the differences between three types of perceptions: the perceptions of the occurrence of critical incidents in tutorial groups, the perceptions of whether these incidents inhibit tutorial group functioning and the expectations students have of the role of the tutor with respect to these incidents. Variations in these student perceptions were also investigated for different training levels. The subjects consisted of a stratified random sample of 200 students from first, second, third and fourth year at the Medical School of the University of Maastricht. We used a questionnaire that consisted of a list of 36 statements and related descriptions of critical incidents in the tutorial group. Six potential success inhibitors (lack of elaboration, lack of interaction, unequal participation, lack of cohesion, difficult personalities and lack of motivation) were assumed to underlie the statements of the questionnaire. Students were asked to rate each incident on a five-point Likert scale for the three types of perceptions. The major finding of this study was that there are significant differences between the three types of student perceptions. We also found that there are significant differences between perceptions of students in each of the four academic years. We conclude that all potential success inhibitors play a role in explaining dysfunctional tutorial groups. Motivational influences seem to have a particularly strong impact on tutorial group function.