A 24-year-old female without previous symptoms or known heart disease consulted a general practitioner with dyspnoea which had slowly worsened over a period of two years. She was treated for asthma, without investigations, until she presented with rapid atrial fibrillation, chest pain and pulmonary oedema necessitating admission to hospital, where she was found to have “mitral” regur-gitation (of the left-sided atrioventricular valve) and congenitally corrected transposition. At operation the grossly regurgitant left-sided morphologically tricuspid valve was replaced by a “top-hat” inverted aortic valve homograft. The procedure resulted in intermittent heart block, needing a pacemaker, and continued myocardial failure which progressed with new right-sided valvar regurgitation. She died a few months later. Post mortem examination confirmed the double discordance, and showed a fistula around the tricuspid valvar prosthesis, left atrial thrombus and changes in the mitral valve. There was also an unsuspected area of old myocardial ischaemia, associated with severe hypoplasia of the circumflex branch of the right-sided coronary artery. This was considered probably to have been of embolic origin.