In the Department of Pathology of Albert Szent-Györgyi Medical University at Szeged in Hungary 37,504 autopsies were performed in the last 30 years and double multiple primary malignant tumours were found in 385 cases (4.2%). In thyroid cancer cases the tumours of other organs were more frequent (22.7%), and these tumour-associations were observed mainly simultaneously, there were no important sex differences. In the most of cases the thyroid cancer was only a side diagnosis beside other malignancies, in the more rare metachronous cases the thyroid cancer was secondary following postoperative irradiation of the first tumour (4 cases of 5). We have seen thyroid cancers most frequently together with lung, breast and digestive system tumours.