Peroxidase-modified amperometric electrodes have been widely studied and developed, not only because of hydrogen- and organic peroxides are important analytes but also because of the key role of hydrogen peroxide detection in coupled enzyme systems, in which hydrogen peroxide is formed as the product of the enzymatic reaction. Many important analytes, such as, aromatic amines, phenolic compounds, glucose, lactate, neurotransmitters, etc. could be monitored by using bi- or multi-enzyme electrodes. In this review the heterogeneous electron transfer properties of peroxidases are discussed as a basis for the analytical application of the peroxidase-modified amperometric electrodes, and examples are given for various peroxidase electrode designs and their application.