IntroductionDifferences in the viewpoints of clinical faculty members and medical students about prioritizing professional norms accepted by the professional community and lack of alignment of these views can lead to distortion of understanding, problems in learning and assessment of professionalism, and failure in students’ professional identity formation. This study aimed to identify the differences in viewpoints of clinical faculty members and medical students about prioritizing the importance and prevalence of professional and unprofessional behaviors among undergraduate medical students.MethodsA multi-stage qualitative study was conducted at Tehran University of Medical Sciences during 2020–2021. At first, a systematic search was conducted to identify professional and unprofessional behaviors using the directional content analysis method. A panel of experts was formed to check the codes obtained from reviewing the literature and to evaluate its compliance with the context. Then, the modified nominal group technique sessions were held with clinical faculty members and medical students to strengthen the codes extracted from the studies and systematically integrate their views to achieve a comprehensive list of professional and unprofessional behaviors in accordance with the context. Finally, a consensus was made among them about prioritizing the importance and prevalence of these behaviors in undergraduate medical students.ResultsA total of 490 codes of professional behaviors and 595 unprofessional behavior codes were identified in the literature review. In the following sessions of the modified nominal group, 13 clinical faculty members listed 105 codes of professional and unprofessional behaviors, and 51 medical students also listed 313 codes. The results of the modified nominal group technique showed that the faculty members reported the importance of unprofessional behaviors higher than professional ones. At the same time, students rated the importance of professional behaviors higher than unprofessional ones. Both faculty members and students rate the prevalence of professional behaviors as high and the prevalence of unprofessional behaviors as low.ConclusionThe results showed a difference of views between clinical faculty members and medical students about prioritizing professional and unprofessional behaviors. It is essential to align their viewpoints to understand, learn and value professionalism to develop a professional identity.