Abstract Rheumatic valve disease remains prevalent in developing countries, but over the last 50 years there has been a decline in the incidence of rheumatic valve disease and an increase in the prevalence of degenerative valve pathology in northern Europe and North America. In all forms of valve disease, the most appropriate initial diagnostic investigation is almost always the echocardiogram. The most common cause is rheumatic valve disease. Other causes include mitral annular calcification, congenital mitral stenosis, infective endocarditis (very rarely), and systemic lupus erythematosus (Liebman–Sachs endocarditis). The important consequences of mitral stenosis are its effect on left atrial pressure, size, and the pulmonary vasculature; it commonly causes atrial fibrillation. Presenting symptoms are typically exertional fatigue and breathlessness; systemic embolism can occur. Characteristic physical signs are irregular pulse, tapping apex beat, loud first heart sound, opening snap, and an apical low-pitched rumbling mid-diastolic murmur.