Background: We tried to evaluate the female fertility and genetic risk to the offspring from the high-dose 131I treatment by assessing stable chromosomal aberration frequencies in pperipheral blood lymphocytes and amniotic fluid and health status of the new-born children of female patients with differentiated thyroid cancer who received therapeutic doses of 131I Materials and Methods: From 2004 to 2007, a total of 889 women had been treated with 131I.