Measurement of transepithelial electrical resistances (TER) is a very common tool for investigations concerning epithelial and endothelial barrier properties. We here introduce two new and powerful techniques for the determination of TERs that might open further applications. The first method takes advantage of the wide spread DC technique and allows to study individual colonies of a cell monolayer grown on waterpermeable filter supports. The second technique is based on AC impedance analysis and enables to determine TERs of cell monolayers grown on gold surfaces.