The Competency-Based Training program in Intensive Care Medicine in Europe identified 12 competency domains. Professionalism was given a prominence equal to technical ability. However, little information pertaining to fellows' views on professionalism is available. A nationwide qualitative study was performed. The moderator asked participants to clarify the terms professionalism and professional behaviour, and to explore the questions "How do you learn the mentioned aspects?" and "What ways of learning do you find useful or superfluous?". Qualitative data analysis software (MAXQDA2007) facilitated analysis using an inductive coding approach. Thirty-five fellows across eight groups participated. The themes most frequently addressed were communication, keeping distance and boundaries, medical knowledge and expertise, respect, teamwork, leadership and organisation and management. Medical knowledge, expertise and technical skills seem to become more tacit when training progresses. Topics can be categorised into themes of workplace-based learning, by gathering practical experience, by following examples and receiving feedback on action, including learning from own and others' mistakes. Formal teaching courses (e.g. communication) and scheduled sessions addressing professionalism aspects were also valued. The emerging themes considered most relevant for intensivists were adequate communication skills and keeping boundaries with patients and relatives. Professionalism is mainly learned 'on the job' from role models in the intensive care unit. Formal teaching courses and sessions addressing professionalism aspects were nevertheless valued, and learning from own and others' mistakes was considered especially useful. Self-reflection as a starting point for learning professionalism was stressed.