Nerve conduction studies are a key component of the electrophysiologic evaluation of the peripheral nerve system, and provide important information about the integrity of the large, myelinated axons, neuromuscular junctions, and muscle. Nerve conduction studies involve eliciting nerve action potentials at sites along a peripheral nerve and recording the response from another site along the nerve or from a muscle innervated by that nerve. Attention to details of test performance, use of well-established normative values, and knowledge of the patterns of abnormality produced by disorders that affect neuronal, axonal, and myelin sheath function are fundamental for proper interpretation of results.