In developed countries, aortic stenosis is the most prevalent of all valvular heart diseases. A manifestation of ageing, the disorder is becoming more frequent as the average age of the population increases. Symptomatic severe disease is universally fatal if left untreated yet is consistent with a typical lifespan when mechanical relief of the stenosis is provided in a timely fashion. Management of mild disease, severe asymptomatic disease, and far advanced disease, and the effect of new percutaneous treatments, provide both controversy and exciting promise to care of patients with aortic stenosis. We discuss these issues in this Review.