Aim: The potassium channel Kv7.1 is expressed in the heart where it contributes to the repolarization of the cardiac action potential. In addition, Kv7.1 is expressed in a variety of epithelial tissues where it plays a role in salt and water transport. Mutations in the kcnq1 gene can lead to long QT syndrome and deafness and several mutations have been described as trafficking mutations. To learn more about the basal mechanisms that regulate Kv7.1 surface expression, we have here investigated the trafficking of Kv7.1 during the polarization process of the epithelial cell line MDCK. Methods: MDCK cells were used as a model system to study the trafficking of Kv7.1 during the polarization process using a modified version of the classical calcium switch. The localization of Kv7.1 was analyzed at different time points during the switch by confocal imaging, surface biotinylation and Western Blots. Results: We discovered that Kv7.1 exhibits a very dynamic localization pattern during the calcium switch. When MDCK cells are kept in low calcium medium Kv7.1 is mainly observed in the plasma membrane. During the first hours of the switch, Kv7.1 is removed from the plasma membrane and an intracellular accumulation in the endoplasmic reticulum (ER) is observed. The channel is retained in the ER until the establishment of the lateral membranes at which time Kv7.1 is released from the ER and moves to the lateral membrane. Conclusion: Our results demonstrate that Kv7.1 surface expression is regulated by mechanisms involved in epithelial cell polarization. The process is highly dynamic with Kv7.1 being surface expressed, then ER-retained and later moving back to the plasma membrane. This regulation of Kv7.1 localization might prevent Kv7.1 channels from being trapped in the apical membrane after the initiation of the polarization process and our results provide important clues to regulatory mechanisms involved in Kv7.1 surface expression in vivo.