-The Chernobyl nuclear accident, which occurred on April 26th, 1986, resulted in widespread long-term contamination, mainly due to 137 Cs, of large territories where populations live. A project was initiated to assess the 137 Cs body burden and health status, not limited to radiation-induced pathologies, for all children living in a highly contaminated district in Belarus; the aim was to provide detailed information for parents worried about their children's health, without the intention of quantifying the radiation-induced risk. In total, about 2500 children benefited from these check-ups, which included approximately 30 parameters and were repeated three times between 2005 and 2009. The internal 137 Cs burden was rather low; about 50% of children had less than 10 Bq kg −1 . The health indicators reported in this paper are the global health status, physical development, and frequencies of thyroid modifications and cardiac dysfunctions. The 137 Cs body burden or density deposition did not appear to be strongly associated with these health indicators; other parameters, such as quality of living conditions and rural or urban residence, appeared to be more important. The aim of the project was achieved, as the results provided a global overview of the health status and level of internal contamination of children living in a contaminated territory about 20 years after the accident.