The physiological responses of sexual arousal which have been well described by Masters & Johnson, has led to the objective measure of sexual arousal. Penile tumescence is an accepted and reliable method of evaluating sexual excitability. The correlation between Penile tumescence measure and the subjective assessment of sexual arousal is high and has been reported in the range of 0.55 to 0.74 in various studies. The development of simple and inexpensive transducers for measuring penile tumescence has been a significant factor in the empirical research into sexual offenders and has led to major advances in the identification of deviant sexual arousal. This, in turn, allows more specific treatment strategies to be developed and also provides a method for evaluating and monitoring the response to treatment. Electrical bioimpedance is a technique that enables the non-invasive measurement of blood flow by the quantification of changes in the electrical conductivity of a body segment or a tissue sample and is being adapted for penile tumescence testing.