In April 2005, a 72-year-old woman with pulmonary sarcoidosis exhibited focal (18)F-fluoro-2-deoxyglucose ((18)F-FDG) uptake in her heart on (18)F-FDG positron emission tomography (PET). Although Japanese guidelines for diagnosing cardiac sarcoidosis were not met at this point, electrocardiography, echocardiography, and magnetic resonance imaging became diagnostic for cardiac sarcoidosis 1 year later. In the present case report, the potential of (18)F-FDG PET in the early recognition of cardiac sarcoidosis in comparison with other imaging modalities is discussed.