Electromyography (EMG) is a well known method used for many years to objectively evaluate the functions of the peripheral nervous system. It is now an indispensable part of examination of each patient with a suspicion of neuromuscular disease. It should be noted that although EMG examination provides accurate facts about the presence and severity of functional nerve damage, this method cannot provide any insight into the anatomy of the nerves, or the state of the surrounding tissue. Thus, there is a need to have additional diagnostic procedure besides EMG that would enable the full insight into a peripheral nerve. For the last two decades, there is a clear trend for more frequent use of ultrasound (US) in the diagnosis and monitoring of various diseases of the peripheral nerves. Indications for the US in peripheral nerve disorders are numerous, but this method is often applied in suspected compressive mononeuropathy, traumatic nerve damage (especially of the brachial plexus), in rare primary nerve tumors and in neurocutaneous diseases, as well as some immune-mediated neuropathies. The lecture will present the basic ultrasound principles in the diagnosis of these disorders, with illustrative examples from clinical practice.