PURPOSE: Social media influences the practice of healthcare professionals. Existing studies on online professionalism and social media are scarce, and most used survey-based methods. This qualitative study explores online professionalism in healthcare among medical students and residents and maps their perceived educational needs. METHOD: Semi-structured focus group interviews were conducted between September 2019 and June 2021 to explore the perceptions of online professionalism among Dutch medical students and residents. Interviews were recorded, transcribed, and thematically analyzed iteratively and independently by two researchers. RESULTS: Seven one-hour focus groups were conducted among 24 medical students and 22 residents. Patient requests from social media directed at students and residents occurred, none were accepted. Upon patient confidentiality breaches on social media, peers tended to speak up to one another. Participants voiced that clarity about the 'grey areas' - where distinguishing between right and wrong is difficult - of social media use is needed. CONCLUSIONS: Social media use was widespread among participants and patients' requests directed at students and residents did occur. They were unlikely to speak about online professionalism lapses to their peers unless a breach of patient confidentiality is involved. Educators should focus on enhancing the professional use of social media in both undergraduate and postgraduate training.