The authors report the case of a 58-year-old woman suffering from an intra-thyroid metastasis of a carcinoma of the colon for which she had undergone surgery two and a half years previously. This adenocarcinoma was, furthermore, clinically and radiologically "cured". The metastasis was accompanied by a cervical swelling and paralysis of the left recurrent laryngeal nerve, the reason for the consultation. Subsequent examinations revealed multiple lung metastases. Despite combined treatment with radiotherapy and chemotherapy, there was later development of further multiple metastases, in particular cerebral. The authors review the literature concerning this type of tumour. Particular emphasis is placed upon tumours with a high malignant potential, such as the naevo-carcinoma, together with tumours of neighbouring structures, in particular the upper airway and digestive tract, all of which may spread to the thyroid. There have nevertheless been other cases of thyroid metastasis of a carcinoma of the colon. One of the very first was that of Rankin and Fortune, published in 1936.