Aim To determine whether analysis of unsolicited healthcare complaints specifically focusing on unprofessional behaviour can provide additional information from the patients' perspective. Methods A qualitative study with content analysis of healthcare complaints and associated judgements using complaints filed from 2004 to 2009 at the complaints committee of a tertiary-referral centre. Subsequent comparison of the resulting categories of poor professionalism to categories perceived relevant by physicians in a previous study was performed. Results 137 complaints (98%) yielded 46 different unprofessional behaviours grouped into 18 categories. The element 'perceived medical complications and error' occurred most commonly (n1/477), followed by 'having to wait for care' and 'insufficient or unclear clarification' (n1/452, n1/448, respectively). The combined non-cognitive elements of professionalism (especially aspects of communication) were far more prominently discussed than cognitive issues (knowledge/skills) related to medical error. Most categories of professionalism elements were considered important by physicians but, nevertheless, were identified in patient complaints analysis. Some issues (eg, 'altruism', 'appearance', 'keeping distance/respecting boundaries with patients') were not perceived as problematic by patients and/or relatives, while mentioned by physicians. Conversely, eight categories of poor professionalism revealed from complaint analysis (eg, 'having to wait for care', 'lack of continuity of care' and 'lack of shared decision making') were not considered essential by physicians. Conclusions The vast majority of unprofessional behaviour identified related to non-cognitive, professionalism aspects of care. Complaints pertaining to unsatisfactory communication were especially noticeable. Incongruence is noted between the physicians' and the patients' perception of actual care.