Serpins are a superfamily of related protease inhibitors with common structural features and inhibitory mechanisms. However, SERPINA 14 in mammals does not have inhibitory activity against most known proteases. Rather, it may have an immunoregulatory role in mammals to prevent rejection of the fetal allograft by inhibiting lymphocyte proliferation and natural killer cell function. In the pig, SERPINA14 is involved in iron transport to the fetus by binding to and stabilizing the iron-binding protein uteroferrin (ACP5). In chickens, these very little known about serpins in chickens. Therefore, we investigated the expression patterns of serpin genes in the oviduct of adult hens and in the oviduct of 37-day-old chicks treated with an estrogen analogue, diethylstilbestrol (DES). Results indicated that SERPINB3 and SERPINB11 genes were highly expressed in oviducts of DES-treated chicks, but not in oviducts of control chicks. Both SERPINB3 and SERPINB11 transcripts were localized specifically to the gland-like areas of oviducts of DES-treated chicks. Immunohistochemical analyses confirmed that SERPINB3 and SERPINB11 proteins were present in the gland-like area and luminal epithelium of the oviducts of DES-treated chicks. Collectively, the results suggest that SERPINB3 and SERPINB11 are expressed in response to estrogens and they have distinct functions related to development and differentiation of the mature oviduct in hens.