The cytokine network is involved in the immune system communication. As estrogens influence the cytokine expression in mammals, this study investigated the impact of exogenous estrogenic pollutants on selected cytokines in Dicentrarchus labrax. The gene expression of Interleukin 6, Tumour Necrosis Factor a, Transforming Growth Factor beta 1 and Interleukin 1 beta was assessed and accomplished with protein measurements in the blood for the last two. Impacts through 17 beta-estradiol mainly occurred at the beginning of organ regionalisation, thus falling together with a developmentally induced increase of Interleukin 1 beta and Tumour Necrosis Factor alpha gene expression in 102 dph fish. 17 beta-estradiol depressed this modification after 35 days of exposure and the cytokine gene expression tended to be generally down-regulated independently of the 17 beta-estradiol concentrations after 56 days of exposure. This impact was confirmed at the protein level, showing that 17 beta-estradiol affects the fine control of the cytokine network in sea bass. (C) 2013 Elsevier Ltd. All rights reserved.