The prevalence of NTRK1 re‐arrangement was determined in papillary thyroid carcinomas (PTCs) of children from Belarus who had been exposed to radioactive iodine after the Chernobyl reactor accident; 81 tumors were included, all of which were devoid of RET re‐arrangement as analyzed in a current study on genomic alterations in PTC. Oncogenic fusion of the NTRK1 tyrosine kinase domain with the amino‐terminal part of the tropomyosin gene (TPM3/NTRK1, trk) was observed in 5 tumors. A single tumor exhibited a TPR/NTRK1 fusion (TRK‐T2). Reciprocal NTRK1/TPM3 transcripts were found in 4 of 5 tumors with TPM3/NTRK1 re‐arrangement, indicating an intra‐chromosomal balanced reciprocal inversion. No phenotypic differences from other post‐Chernobyl childhood PTCs were detected. As compared with the high prevalence of RET re‐arrangements reported for thyroid carcinomas of children after the Chernobyl reactor accident, NTRK1 re‐arrangements appear rare. Our results confirm that activation of receptor tyrosine kinase genes plays the predominant role in post‐Chernobyl childhood thyroid carcinogenesis. Int. J. Cancer 80:842–847, 1999. © 1999 Wiley‐Liss, Inc.