[en] This paper reports the activities and the results of the research carried out by the Centers participating to the JSP4 project, within the framework of the EU program on the consequences of the Chernobyl disaster. The project was aimed to develop and to control the application of basic principles for the diagnosis, treatment and follow-up of thyroid carcinoma, with special attention to the peculiar requirement of children and adolescents. To this purpose, training in Western European Centers was offered to a number of scientists from Belarus, Ukraine and Russia. Several official meetings were organized to share views and to discuss the progress of the project. A basic protocol for the diagnosis, treatment and follow-up of thyroid carcinoma has been developed and approved by all participating Centers. Hopefully, it will be applied to the new cases and to those already under monitoring. A large part of the protocol is dedicated to the post-surgical treatment with thyroid hormones for the suppression of TSH and with calcitriol for the management of surgical hypoparathyroidism. A detailed protocol to asses iodine deficiency and, eventually, to introduce a program of iodine supplementation has been proposed. The collection of control cases of childhood thyroid carcinoma in non-radiation exposed European countries has been initiated in Italy, France and Germany. This data will be used as control for the post-Chernobyl childhood thyroid carcinomas. Here is reported a preliminary comparison of the clinical and epidemiological features of almost all (n=368) radiation-exposed Belarus children who developed thyroid carcinoma (age at diagnosis < 16 years), with respect to 90 children of the same age group, who, in the past 20 years, have received treatment for thyroid carcinoma in two centers in Italy (Pisa and Rome). Finally, by molecular biology, genetic mutations of the RET proto-oncogene have been found in several samples of thyroid carcinomas provided by the Belarus partners. All together, this project has provided the CIS partners with the most useful information and knowledge in order to allow an effective treatment of the diseased population and, possibly, the prevention in those not yet affected