TENS refers to the application of various pulse current forms for pain relief and improvement of tissue trophism. Since TENS typically uses compensated impulses, the effects in the tissue are not the same as those produced by direct current or pulse current with a direct current component. For this reason, TENS is given its own chapter. There is a wide variety of devices and parameters, but fundamentally two main forms can be distinguished: high-frequency TENS, which uses a relatively high frequency, and low-frequency TENS, which uses a distinctly lower frequency. These methods activate different pain inhibition mechanisms. These differences are discussed in detail. In addition to TENS, there is also interferential current from the medium-frequency range. This method is also used to stimulate nerves through the skin. The applications, advantages, and disadvantages of the various methods are discussed in detail.