Endomyocardial biopsy (EMB) has been established in parallel with the development of percutaneous catheter technology for the diagnosis of cardiac diseases. It was developed in the early 1960 s in Japan by Drs. Konno, Sakakibara and Sekiguchi of Tokyo Women's Medical University. EMB is a valuable and useful, but invasive, modality for making a definite diagnosis in diseases such as myocarditis and secondary cardiomyopathies, which are often difficult to diagnose by imaging modality alone. In the field of heart transplantation, the histology of EMB helps monitor rejection to allografts. In cases of chronic heart failure, fibrosis and degeneration of cardiomyocytes are very important findings of heart remodeling. Recently, molecular biology technology has been applied to EMB specimens to get more detailed information. However, we must also recognize that EMB is an invasive examination that should not be performed without skillful cardiac catheterization experience to avoid complications. In this review as a message from pathologists, we present key cardiac histopathology using EMB, in a way that allows one to imagine whole cardiac pathological conditions. We also describe the current role of EMB and its significance in order to encourage young cardiologists to perform EMB to see another world of pathology.