The cardiac action potential requires a precise timing of activation and inactivation of ion channel subtypes. Deviations, for example, due to blockage of specific voltage-gated potassium channels, can result in live-threatening arrhythmias. Due to the limitations of standard cellular assays based on cells which artificially express only single ion channel subtypes, many potentially interesting compounds are discarded during drug development. More predictive functional assays are required. With the upcoming of human stem-cell derived cardiomyocytes (hiPS-CM) these assays are available, supporting even the design of patient-derived disease models. Microelectrode array systems allow to noninvasively record and evaluate cardiac field action potentials. In this chapter we describe how to cultivate hiPS-CM on two parallelized MEA systems and suggest an experimental strategy for compound tests.