Patch-clamping is an essential technique in the field of ion channel drug discovery and safety pharmacology. Conventional patch-clamp methods provide high data quality and can be applied to a wide variety of cells, but the methods are laborious and time-consuming. Automated patch-clamp (APC) systems in which multi-well planar patch plates are used have been developed to overcome these disadvantages, and they allow data from hundreds to thousands of cells to be obtained in a single day. The recording success rate highly depends on cell types and cell conditions because cells are positioned on the patch holes in a blind manner and only cells that fit to patch holes can be used for recording. The first APC system that was developed, the IonWorks HT system, has been used widely, but it has limitations in regard to success rates and high-throughput ability. The next system, IonWorks Quattro system, uses a population patch-clamp method, and it has provided a high success rate and higher throughput ability. Sophion’s QPatch system yielded data whose quality is similar to that of conventional patch-clamp methods, although precise adjustment of the experimental conditions is necessary to obtain high success rates. This chapter describes the principle of APC systems and their characteristics.