INTRODUCTION: Radionuclide imaging for the diagnosis and monitoring of cardiac involvement in sarcoidosis has advanced significantly in recent years. SOURCES OF DATA: This article is based on published clinical guidelines, literature review and our collective clinical experience. AREAS OF AGREEMENT: Gallium-67 scintigraphy is among the diagnostic criteria for cardiac involvement in systemic sarcoidosis, and it is strongly associated with response to treatment. However, fluorine-18, 2-fluoro-deoxyglucose (FDG) positron emission tomography (PET) is now preferred both for diagnosis and for assessing prognosis. AREAS OF CONTROVERSY: Most data are from small observational studies that are potentially biased. GROWING POINTS: Quantitative imaging to assess changes in disease activity in response to treatment may lead to FDG-PET having an important routine role in managing cardiac sarcoidosis. AREAS TIMELY FOR DEVELOPING RESEARCH: Larger prospective studies are required, particularly to assess the effectiveness of radionuclide imaging in improving clinical management and outcome.