BACKGROUND The number of places available in Ireland and the United Kingdom (UK) for graduate entry to medical school has increased in the past decade. Research has primarily focused on academic and career outcomes in this cohort, but attitudes towards professionalism in medicine have not been systematically assessed. The purpose of this study was to compare the importance of items related to professional behaviour among graduate entrants and their 'school-leaver' counterparts. METHODS This was a quantitative cross-sectional study, conducted in University College Cork (UCC), Ireland. A validated questionnaire was distributed to undergraduate-entry (UG) and graduate-entry (GE) students with items addressing the following areas: Demographic and academic characteristics and attitudes towards several classes of professional behaviours in medicine. RESULTS GE students ascribed greater importance, relative to UG students, to various aspects of professionalism across the personal characteristics, interaction with patients and social responsibility categories. Additionally, in UG students, a significant decrease in perceived importance of the following professionalism items was evident across the course of the degree programme: Respect for patients as individuals, treating the underprivileged and reporting dishonesty of others. Among both groups of students, individual mentoring was rated the most important method for teaching professionalism in medicine. CONCLUSIONS This study is the first comparison of attitudes to professionalism in UG and GE students. This study highlighted important group differences between GE and UG students in attitudes towards professional behaviours, together with different perspectives regarding how professionalism might be incorporated within the curriculum.