Amyotrophic lateral sclerosis or motor neuron disease is a progressive motor system degeneration. Extra motor involvement also occurs, primarily in the form of executive dysfunction. Up to 15% of those with ALS also develop frontotemporal dementia. The pathophysiology of ALS is not well understood. Five percent of cases have a positive family history, and a number of causative and “at risk” genes have been identified. Diagnosis is clinical, and investigations are aimed at excluding other treatable conditions. Optimal management of ALS requires a multidisciplinary team. Most ALS patients develop respiratory failure, and early intervention with noninvasive ventilation can improve survival and enhance quality of life. Patients with ALS should be encouraged to consider an advance directive regarding their end of life.