Hormone release from pancreatic cells, for example glucagon from α-cells and insulin from β-cells, is controlled by the cells’ membrane potentials (Vm), which are in turn finely controlled by multiple classes of ion channels, transporters, and pumps. The perforated whole-cell patch-clamp method represents a direct and well-established way to monitor Vm in individual cells and also to investigate ionic currents (Im) that contribute to determination of Vm. Here a step-by-step guide to obtain various patch-clamp measurements from pancreatic cells in isolated intact human islets is provided. The method requires a standard electrophysiological station and β escin is used as the perforating agent. Select exemplar current-clamp Vm results and voltage-clamp Im results are provide. The electrophysiological characteristics may be used to distinguish pancreatic cell types, for example α-cells vs. β-cells in real time.