Appraisal and revalidation for doctors are often seen as two sides of the same coin, the currency for assuring safe standards of medical practice in the United Kingdom. Both are evidence-based processes: appraisal is formative, forward-looking, developmental and non-punitive; revalidation, on the other hand, is essentially summative, backward-looking, judgemental and potentially punitive. What they have in common is two-fold: the principles to which they work – the seven principles of Good Medical Practice, as defined by the General Medical Council (GMC) – and the information, the evidence streams, that support the process. The evidence is derived from clinical governance systems, and it is therefore these that should give the assurance of quality sought by politicians and the public. Trusts, therefore, have a duty to provide, and the Healthcare Commission a duty to verify, clinical governance systems that give doctors the information they need, to ensure that both appraisal and revalidation are sufficiently robust for supporting doctors and protecting patients. Neither appraisal nor revalidation will deliver on expectation if clinical governance arrangements are poor.