Abstract Thyroid cancer accounts for just under 1 per cent of malignant disease. The prognosis varies from excellent with papillary carcinoma in young people to very poor in anaplastic carcinoma in the elderly. Modified rather than radical dissection of lymph nodes is indicated with well-differentiated tumours. The level of calcitonin in the blood is a sensitive marker for medullary carcinoma occurring either as sporadic or familial disease. The outcome of management in 7 patients with medullary carcinoma indicates that the prognosis is variable and that thyroidectomy is effective treatment.