MUNE is a non-invasive, electrophysiologic method to estimate the number of motor neurons innervating a muscle or group of muscles. The ability to quantitatively estimate the number of surviving motor neurons is useful in the following areas: (a) clinically for diagnosis of neuromuscular disorders; (b) as an endpoint measure in clinical drug trials for lower motor neuron disorders; and (c) as a tool to obtain insight into the natural history and pathophysiology of lower motor neuron disorders. Relevant lower motor neuron disorders include amyotrophic lateral sclerosis (ALS), spinal muscular atrophy and Charcot-Marie-Tooth inherited neuropathies. To date, there has been no formal meeting of investigators working in the field of MUNE. The symposium is designed to: (a) review and discuss the methods, advantages and disadvantages of each MUNE technique; (b) review previous applications of MUNE in research and clinical trials; (c) formulate plans for further studies to clarify issues that affect the accuracy and utility of MUNE. The symposium and workshop included an international roster of approximately 20 invited speakers who presented formal talks on the methods, assumptions, techniques and applications. Presentations by representatives from EMG equipment manufacturers were given. Each talk was followed by a discussion session, and groups of talks by a panel discussion. This publication is meant to serve as a manual for the theory and practice of MUNE. Currently, there is no book addressing MUNE.