A 27-year-old black woman with cardiac failure, angina pectoris and Raynaud's syndrome is presented. Skin biopsy and barium studies established the diagnosis of scleroderma (progressive systemic sclerosis (PSS)). Systemic lupus erythematosus (SLE) was strongly suggested by the results of immunological studies and increasing severity of renal failure. Because of the possibility of a cardiomyopathy, cardiac catheterization, selective coronary angiography and right ventricular endomyocardial biopsy were carried out but failed to show any histological features of either SLE or PSS. The patient went into progressive renal failure despite immunosuppressive therapy and plasmapheresis and died; consent for autopsy was refused. A final diagnosis of mixed connective tissue disease (MCTD) was made. The salient features of cardiac involvement in SLE, PSS and MCTD are outlined.