Text in English & French. Proceedings of the first European Congress on Medullary Thyroid Carcinoma held in Paris (France), 15-17 November 1990. Thirty years have passed since the description by Hazard, Hawk and Crile of medullary cancer of the thyroid. Improvement in the know-ledge of the disease has concerned all its aspects, such as malignancy, endocrinology, genetics and epidemiology. This is a time of exciting dis-coveries in basic research but also of European collaboration. So, the Groupe d'Etude des Tumeurs A Calcitonine has initiated a congress de-voted to this tumour, in order to point out and transmit a statement of the question as full as possible and to open the way to a more collabo-rative approach of the disease.