This excellent article summarises the current diagnostic difficulties with an endocrine gland that frequently produces nodules, some of which may harbour malignancy. At 50 years of age and over there is about a 50% chance of having a nodule; at 90 years it is almost a certainty. Clinically insignificant thyroid cancers discovered incidentally at autopsy have been estimated to occur in up to 36%, and with better diagnostic imaging they are found easily. A good diagnostic algorithm is presented for the evaluation of a thyroid nodule with an up to date detailed risk factors assessment that might stimulate further investigation. Large one-off radiation exposure occurring after 20 years of age has not been proven to increase thyroid malignancy incidence. However radiation in childhood, even from CT and PET imaging, should be enquired about in any taken history. The commonest useful characteristics on ultrasound for the detection of malignancy are still microcalcifications, size greater than 2cms and entirely solid composition. Molecular markers are explored in more detail in another paper that is reviewed below. When considering intervention, attention is rightly drawn to the competing risk of death from other co-morbidities, given that the 20-year survival for papillary cancer (tumours of any size confined to the gland) is 99%.