Abstract
The study goal was to investigate thyroid cancer morbidity in population groups affected by the Chernobyl catastrophe. The study period comprised 1994-2006 for clean-up workers and 1990-2006 for Chernobyl evacuees and residents of contaminated territories. A significant increase of thyroid cancer incidence was registered in all observed population groups. The most significant excess over the national level was identified in clean-up workers. This amounted to a factor of 5.9, while it was 5.5 for the evacuees and 1.7 for the residents. The highest thyroid cancer risk was observed in persons exposed to radioiodine in childhood and adolescence.