Incidence, pathogenesis, diagnostic strategy and indications for treatment. Aortic stenosis is a serious disease which should be diagnosed early because of the good operative results. For this reason it is important to be aware of the disease particularly in the elderly and in patients with a history of rheumatic fever (e.g. immigrants). The diagnosis should be suspected in the patient with one or more of the three following symptoms: dyspnoea, angina pectoris and syncopes, and who has a systolic ejection murmur at the base of the heart with transmission to the neck and a reduced or absent second heart sound. First priority next to routine examinations (stethoscopy, ECG, x-ray of the chest) is referral to echocardiography. The echocardiographic results in combination with the patient's history and the clinical examination almost always form a sufficient basis for the timing of the operation. Indications for operation are given.