The MDCK cell line provides a tractable model for studying protein trafficking, polarity and junctions (tight, adherens, desmosome and gap) in epithelial cells. However, there are many different strains of MDCK cells available, including the parental line, MDCK I, MDCK II, MDCK.1, MDCK.2, superdome and supertube, making it difficult for new researchers to decide which strain to use. Furthermore, there is often inadequate reporting of strain types and where cells were obtained from in the literature. This review aims to provide new researchers with a guide to the different MDCK strains and a directory of where they can be obtained. We also hope to encourage experienced researchers to report the stain and origin of their MDCK cells.