The line of epithelial-like Chinese hamster ovary (CHO) cells was initiated by T.T. Puck in 1957. Since then, CHO cells have become a widely used mammalian expression system in industry and science. This paper discusses the different features of CHO cell physiology as well as the specific aspects of using these cells for ion channel studies; among the discussed features are the culturing and transfection of CHO cells, details of electrophysiological recordings from them and applications for the study of ion channel physiology and pharmacology. Examples of successful reconstitution of mammalian ion channels in CHO cells discussed in the paper include reconstitution of KCNQ channel regulation by muscarinic acetylcholine receptors and the study of the amiloride-sensitivity of epithelial sodium channels (ENaC).