After a period during which cardiac papillary fibroelastomas were considered incidental autopsy findings cerebral and coronary arteries embolism proved their aggressiveness. Echocardiography is now able to identify them and surgical resection is rapidly required. Sea anemone like macroscopic pattern is characteristic with finely villous masses, each frond being at microscopical examination formed by a central fibroelastic core surrounded by a myxomatous layer overlied by endothelial cells. Histogenesis remains elusive and we tried to clarify it by immunohistochemical analysis of 8 of the 20 cases studied (10 autopsies, 10 surgical resections). Morphological and immunohistochemical data show that endothelial cells play the most important part in abnormal formations.