Cardiac involvement in patients with sarcoidosis is an important consideration for those who are concerned with this strange disease. Sarcoidosis is not an acute malignant disease but may be noticed at the time of sudden, expected death as fatal myocardial sarcoidosis at autopsy. Even with modern advances in our ability to diagnose heart disease, cardiac sarcoidosis is still often overlooked because of its subclinical disease progression. In view of this, an extensive review of previously published literature and of our own case analyses has been carried out because of the authors' long-term experience with performing Konno's endomyocardial biopsy, which was originally developed in 1962 at the author's institution. However, the sensitivity of endomyocardial biopsy in detecting sarcoid granuloma is low (20-30%), and, instead, various kinds of nongranulomatous pathologies are often seen. During the course of our research it was found that there might exist a racial difference in cardiac sarcoidosis. Cardiac death was much more frequent in Japanese patients. The possibility that heart disease in sarcoidosis is caused by cor pulmonale due to advanced pulmonary fibrosis should be reevaluated because only a limited amount of background data is available. The author's review clarified the fact that cardiac sarcoidosis is caused by myocardial or pericardial involvement, resulting in various kinds of bradyarrhythmias or tachyarrhythmias and/or congestive heart failure. Electrocardiographic (ECG) and Holter monitor readings provide a simple and effective method for early detection of this disease. The incidence of ECG abnormalities in a total of 963 sarcoidosis patients was 22.1%, which was more frequent than that of the sex- and age-matched healthy control subjects (17.9%; p < 0.025). Echocardiography and radionuclide studies also provide useful clinical information. Careful follow-up and early corticosteroid administration followed by small maintenance doses may prevent the progression of the disease and improve prognosis. Owing to the progress in antiarrhythmic drugs and pacemaker implantation, the primary cause of death in cardiac sarcoidosis has changed from sudden death (1976 report) to congestive heart failure (1985 report).