Abstract The hypereosinophilic syndrome characteristically involves multiple organs. Its most severe debilities are associated with cardiac and central nervous system complications. Endothelial damage can result in intracardiac thrombosis, endocardial fibrosis and progressive congestive failure. Computerized tomography is of value in making the diagnosis of an intracardiac mass. Simultaneous evaluation of the pericardiac and extracardiac structures may aide in the distinction of a thrombus from a neoplasm.