Polycystic ovary syndrome (PCOS) is a true syndrome, being a heterogeneous collection of signs and symptoms that gathered together form a spectrum of a disorder with a mild presentation in some, whilst in others there is a severe disturbance of reproductive, endocrine and metabolic function. There has been much debate about phenotype and, more recently, genotype. There has also been scepticism in some quarters, with a feeling that we may be looking at one end of a spectrum that is in reality 'normal', or perhaps a consequence of the modern disease of obesity. Whilst the polycystic ovary is at the centre of the syndrome, it is external effects such as hyperinsulinism, that influence its expression. There is no consensus on the definition of PCOS and so studies that compare epidemiology and treatments often have very different starting points, and so cannot be compared. In this debate we wish to re-explore our current thinking on PCOS, with a particular emphasis on the British and European perspective and invite others to contribute to the discussion which could form the basis for an international consensus.