A 27 year old woman was hospitalized for progressive dyspnea, fatigue and retrosternal chest pain. She had progressive cardiac enlargement with clinical and laboratory confirmation of a dilated cardiomyopathy. Transvenous percutaneous right ventricular endomyocardial biopsy yielded a specimen showing a noncaseating granuloma. The patient's dyspnea responded dramatically to steroid therapy with corresponding improvement in radiographic and echographic measures of ventricular performance. This case illustrates the problem of diagnosing cardiac sarcoidosis when there is no apparent evidence of other organ involvement.