Displacement of the origin of the tricuspid valve into the right ventricle, redundancy of its leaflets and tricuspid incompetence are all present to varying degrees in Ebstein's disease. Cardiac arrhythmias are a common feature. Presentation in infancy with severe displacement of the valve, right-sided heart failure, cyanosis and gross cardiomegaly are the classic features. More recently, echocardiography has revealed a group presenting with arrhythmias but with no significant haemodynamic disturbance, or with an asymptomatic murmur who have a normal or near normal chest radiograph and mild displacement of the valve. Before the availability of echocardiography, most of this group escaped diagnosis as there were insufficient indications for cardiac catheterisation.