Assessment of the professional behaviour of doctors is increasingly recognized as an essential component of doctors' training (Ben-David et al., 2004) with equally important implications for doctors in permanent posts. TAB is a proforma for such assessment using a 360 degree process in which up to 15 colleagues of a doctor assess that doctor's professional behaviour. The pro forma is presented, together with discussion of the format and approach developed, with particular reference to the General Medical Council document "Good Medical Practice". We report on initial piloting of the approach in two UK NHS hospital trusts. In total 440 assessments of 30 doctors were completed. Data regarding intra-observer and inter-observer variation indicate that the process is reliable, practical and consistent. We believe this approach may represent a workable way ahead to promoting appropriate professional behaviour on the part of medical trainees and that it offers potential for re-validation of hospital consultants. There is a clear need for further development and evaluation of this approach, most notably its acceptability and value to all involved.