In addition to our previous reports which are based on the work of the Japanese Sarcoidosis Committee, this communication reports the analysis of expanded case material, evaluation of endomyocardial biopsy in 8 biopsied and 7 autopsied cases, and the effects of steroid and pacemaker therapy. 1. Out of 96 autopsied cases of sarcoidosis, 55 cases have been determined by us as being fatal myocardial sarcoidosis. Additionally, analysis of sarcoidosis patients who were clinically assessed as having cardiac dysfunction was made through the literature and in 17 cases a questionnaire review of the reported cases in Japan was made. It was noted that out of a total of 72 cases, there was a high incidence of cardiac sarcoidosis (fatal myocardial sarcoidosis + sarcoidosis with cardiac dysfunction) in 40-59 year-old women. 2. The modes of cardiac death in fatal myocardial sarcoidosis in 55 cases were: sudden death 20 cases (36.4%); congestive heart failure 10 cases (18.2%); arrhythmia 9 cases (16.4%): Adams-Stokes Syndrome (except sudden death) 8 cases (14.5%); cardiogenic shock 1 case (1.8%); pacemaker death 1 case (1.8%); pulmonary infarction 1 case (1.8%) and unknown 5 cases (9.1%). 3 . Expectancy of a definite diagnosis of endomyocardial biopsy which was made by an imitation endomyocardial biopsy in 7 autopsied cases of fatal myocardial sarcoidosis was 62.8% from the right ventricle and 46.9% from the left ventricle. When such pathology as a distinct scar or acute inflammatory change is incorporated, the possibility of the usefulness of the biopsy increases. Examples of 8 biopsied cases were shown. 4. Ultrastructural findings of epithelioid cells and giant cells in a case of a 42-year-old female in whom endomyocardial biopsy was performed from the right ventricle were described. 5. Our view on the nature of giant cell myocarditis was discussed. This is not a disease entity but a histopathological entity. 6. Evaluation of steroid therapy in cases with fatal myocardial sarcoidosis and with cardiac dysfunction revealed that it was effective in 5 out of the 14 cases of the former group (35.7%), and 10 out of the 14 cases of the latter group (71 .4%). 7. Pacemaker implantation, either temporary and/or permanent, was made in 9 of the 55 cases (16.5%) of fatal myocardial sarcoidosis and in 6 of the 17 cases (35.5%) of sarcoidosis with cardiac dysfunction. In the former group, the pacemaker was effective for a certain period of time but finally death occurred. In the latter group, pacemaking was effective.