[en] The histological verification of thyroid carcinoma that have occurred in children in the contaminated areas of the Russian Federation after Chernobyl has been performed by pathologists from Obninsk and Cambridge. Formalin fixed material and paraffin blocks of 10 cases of childhood thyroid cancer were received from different hospitals in Russia during 1993-1995. 4 of the cases were female, and 6 male. In one of these cases the material available in Cambridge unfortunately showed no tumor. Of the other 9 cases, all were papillary carcinomas. 5 showed the solid follicular pattern, predominant in younger children in the UK and forming the great majority of the recent childhood cases in both Belarus and the Ukraine. 2 were predominantly oxyphil carcinomas which were classified with papillary carcinomas on both architectural and cytological grounds, and 2 showed the features of the classic type of papillary carcinoma, predominant among the older children in the UK. All children came from areas contaminated by fallout from the Chernobyl accident, with 6 from Bryansk 1 from Kaluga and 3 from Tula. All cases were confirmed by immunohistochemistry and in situ hybridization for thyroid differentiation markers. The oncogenes ret, met and p53 were also studied by immunohistochemistry