We describe the case of a 50-year-old woman who was admitted to a pheriferal department for heart failure. The echocardiography revealed a small mass measuring about 1.3 x 1.0 cm adhering to the non-coronary cusp of the aortic valve, mild dilated cardiomiopathy and severe biventricular dysfunction. This mass had erroneously been considered a thrombotic lesion, so the patient was treated with thrombolysis and heparin e.v. Only after a transoesophageal echocardiography a tumour cardiac mass was suspected. The diagnosis of fibroelastoma was confirmed by MRI and then from the anatomic and histoligical definition after surgery.