In this retrospective study, we wondered whether there is a link between CHD4 and NOX4 protein expression in malignant thyroid tissues.<h4>Methods</h4>We explored CHD4 protein expression by immunostaining analysis in 86 human thyroid tissues: 44 thyroid tumor tissues [28 classical forms of PTCs (C-PTCs), 13 follicular variants of PTCs (F-PTCs), and three anaplastic thyroid carcinomas (ATCs)] and 42 of their normal adjacent tissues (NATs). Here, CHD4 is linked to thyroid gland undifferentiated (anaplastic) carcinoma.