Breast cancer has a poor prognosis due to its strong metastatic ability. Accumulating data present ether à go-go (hEag1) K+ channels as relevant players in controlling cell cycle and proliferation of non-invasive breast cancer cells. However, the role of hEag1 in invasive breast cancer cells migration is still unknown. In this study, we studied both the functional expression and the involvement in cell migration of hEag1 in the highly metastatic MDA-MB-231 human epithelial breast cancer cells. We showed that hEag1 mRNA and proteins were expressed in human invasive ductal carcinoma tissues and breast cancer cell lines. Functional activity of hEag1 channels in MDA-MB-231 cells was confirmed using astemizole, a hEag1 blocker, and a specific siRNA targeting this channel (sihEag1). Using patch-clamp technique, calcium imaging and Boyden chambers assays, we demonstrated that blocking or silencing hEag1 depolarized the membrane potential and reduced both Ca2+ entry and MDA-MB-231 cell migration without affecting cell proliferation. Recent studies have reported that Ca2+ entry through Orai1 channels is required for MDA-MB-231 cell migration. Down-regulation of hEag1 or Orai1 expression reduced Ca2+ influx and cell migration with similar efficiency. Interestingly, no additive effects on Ca2+ influx or cell migration were observed in cells co-transfected with sihEag1 and siOrai1. Finally, we found, by immunochemistry, that both Orai1 and hEag1 are expressed in invasive breast adenocarcinoma tissues and invaded metastatic lymph node samples (LNM+) Furthermore, in LNM+, high hEag1 expression level was associated with high Orai1 expression level, and inversely. These data supported the possibility of a link between hEag1 and Orai1 in pathological conditions. In conclusion, this study is the first to demonstrate that hEag1 channels are involved in the serum-induced migration of breast cancer cell by controlling Ca2+ entry through Orai1 channels. hEag1 may therefore represent a potential target for the suppression of breast cancer cell migration, and thus prevention of metastasis development.