Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that results in progressive loss of bulbar and limb function. Patients typically die from respiratory failure within 3 years of symptom onset. The incidence of ALS in Europe is 2-3 cases per 100,000 individuals in the general population, and the overall lifetime risk of developing the disease is 1:400. ALS is familial in 5% of cases, and shows a Mendelian pattern of inheritance. ALS is recognized to overlap with frontotemporal dementia. Diagnosis is made on clinical grounds, using internationally recognized consensus criteria, after exclusion of conditions that can mimic ALS. The Revised ALS Functional Rating Scale is currently the most widely used assessment tool; scores are used to predict survival, and have been employed extensively in clinical trials. Riluzole remains the only effective drug, and extends the average survival of patients by 3-6 months. Optimal treatment is based on symptom management and preservation of quality of life, provided in a multidisciplinary setting. The discovery of further effective disease-modifying therapies remains a critical need for patients with this devastating condition.