Background: Training of doctors in The Netherlands seeks to develop clinical competences including professional behaviour. Behaving as a professional is not just a desirable trait but a clearly stated requirement for doctors and medical students. Results: We designed an educational theme, Professional Behaviour (PB), as a longitudinal thread throughout our six-year curriculum after defining PB as "The observable aspects of practising professionalism". This definition was translated into a set of practical skills that can be observed: "The ability to deal with tasks, to deal with others and to deal with oneself". We assess PB 29 times in the course of the medical curriculum. Students with an unsatisfactory PB do not get their degree irrespective of their medical knowledge. We train teachers to identify and report unprofessional student behaviour, and we offer these students interventions and support. Conclusions: With the educational theme "Professional Behaviour" we have defined PB for our institute and firmly embedded it in the medical curriculum. We use workplace learning and role models for teaching PB. Different teachers carry out multiple formative and summative assessments, using standardized assessment scales. With these measures we intend to promote a culture of excellence in PB in our institute. © 2013 Informa UK Ltd. All rights reserved: reproduction in whole or part not permitted.