Polycystic ovary syndrome (PCOS) is a common endocrine disorder that is associated with recurrent miscarriage. Despite the many studies that have investigated the prevalence of PCOS in recurrent miscarriage, the extent to which PCOS contributes remains highly uncertain. The majority of these studies have used the polycystic ovary morphology alone to define PCOS and the results are extremely variable due to a variety of diagnostic and selection criteria used. Only a very small number of studies have investigated the prevalence of hyperandrogenaemia in recurrent miscarriage. Most crucially, to the authors' knowledge, there is not yet a single publication which has investigated the true prevalence of the complete syndrome of PCOS in recurrent miscarriage using the Rotterdam criteria. Hence there is an urgent need to reappraise the prevalence of PCOS in recurrent miscarriage using the Rotterdam criteria. The possible mechanisms by which PCOS could cause recurrent miscarriage are considered: hyperandrogenaemia, obesity and hyperinsulinaemia are the most likely candidates, although further work is clearly needed. This paper also reviews the possible treatment options for women diagnosed with recurrent miscarriage associated with PCOS. There is some evidence to suggest that weight loss, ovarian drilling and metformin could help to reduce the rate of miscarriage.