Cowden syndrome (CS) is a rare inherited condition characterised by multiple hamartomas in a variety of tissues from all three embryonic layers. It is a cancer predisposition syndrome with an increased risk of developing malignancy in many tissues but especially breast, thyroid and endometrium. It is inherited in an autosomal dominant manner with ∼80% of patients having a germ-line mutation of the PTEN tumour suppressor gene. Presenting signs and symptoms are highly non-specific. Nevertheless clinicians should be able to recognise this syndrome so that patients may be screened for cancerous growths and afforded the opportunity to have genetic testing to assist them and their family members in making medical management decisions. We present a review of this unusual but important condition with particular emphasis on the diagnostic criteria, clinical features, genetics, management and surveillance.