A variety of investigations on peroxiredoxins (Prxs) in different types of cancer have been carried out, but the estrogen-related function of Prxs in breast cancer has not yet been studied. In order to study the involvement of Prxs in the growth of breast cancer cells by estrogen, we evaluated the effect of mitogenic estrogen metabolites on the expression of Prx isoforms (I to VI) in MCF-7 cells and found that the transcript/protein expression of Prx IV was significantly induced by 16alpha-hydroxyestrone (OHE1) under both serum-free and serum conditions. In addition, treatment with Prx IV-specific siRNA significantly inhibited the 16alpha-OHE1-induced proliferation of MCF-7 cells. These results suggested that Prx IV involved in the 16alpha-OHE1-induced proliferation of MCF-7 cells has a proliferative effect and may be related to cancer development or progression.