This chapter deals with intrabody communication using contact electrodes in the frequency band of 0.1 MHz to 100 MHz. It reviews some methods of intrabody communications and some transmission characteristics. The chapter discusses issues in practical circuit design, such as electrode arrangement and impedance matching in detail based on numerical analyses and experimental results. T. Handa et al. developed an electrocardiogram monitoring system using an intrabody communication system with contact electrodes. In intrabody communication systems using capacitive coupling, all electrodes are detached from the human body. The carrier frequency for systems using the transversal electrode arrangement is expected to be lower than several megahertz, because the longitudinal electrode arrangement shows better transmission characteristics at 10 MHz. The most efficient electrode configuration has a single contact electrode for the stationary transmitter box and two contact electrodes for the receiver on the wrist.