Endomyocardial samples from the right ventricle of 100 patients were taken by a Stanford University technique but only 93 of them were good for histology. Samples came from cardiomyopathy (29 patients) and other clinical diagnoses (64 patients). Cardiomyopathy could be proved (3,4%) or conceded (58,6% by histology. In the group of other clinical diagnoses histopathological myocardial finding was not characteristical (53%) or was normal (47%) Light-optical endomyocardial biopsy seems to be a facultative approach of poor effect in cardiomyopathy. We are of the opinion that a more complex examination could ensure better diagnostic conclusions.