The prognosis of sarcoidosis often considered as “benign” is significantly changed in the presence of a cardiac localization. An in-depth interview, a clinical examination together with ECG are often for most of sarcoidosis. Certain conditions (severe multisystemic sarcoidosis, rares localizations in particular neurological, renal, gastric) lead to necessary investigations: Holter ECG, echocardiography, thallium scintigraphy with dipyridamole test, PET scanner and MRI in order to identify infraclinical presentations. Diagnosis relies on guidelines of Japansese criteria, but can benefit from MRI and PET scanner even though their place is not yet clearly defined in clinical pratice. Diagnosing cardiac sarcoidosis means deciding an immunosuppressive treatment. It is highly important to gather all criteria to validate a consistent diagnosis or at least a high probability. In order to best adapt therapy, a coordinated patient care involving the cardiologist and the sarcoidosis specialist is necessary.Le texte complet de cet article est disponible en PDF.