Amyotrophic lateral sclerosis is a progressive, paralyzing illness that is invariably fatal. It has been neglected until recently because there was only a poor understanding of pathogenesis and no treatment. Physicians often experience a sense of helplessness and frustration in conveying the diagnosis truthfully to patients and in helping them to cope with advancing disability and the prospect of death.A review of amyotrophic lateral sclerosis with respect to clinical features, pathological findings, functional and physiologic studies, pathogenesis, therapeutic approaches, and patient care. It is an international effort, with its three editors from the United States, France, and the United Kingdom and 57 other contributors, all of whom are acknowledged experts in the field.