Primary malignant cardiac tumors (cardiac angiosarcomas) are exceedingly rare. Since there are initially nonspecific or missing symptoms, these tumors are usually diagnosed only in an advanced, often incurable stage, after the large tumor mass elicits hemodynamic obstructive symptoms. A 59-year-old female presented with symptoms of cerebral ischemia. A computed tomography (CT) scan showed changes suggestive of stroke. Transesophageal echocardiography revealed an inhomogeneous, medium-echogenic, floating mass at the roof of the left atrium near the mouth of the right upper pulmonary vein, indicative of a thrombus. At surgery, a solitary tumor was completely enucleated. Histologically, cardiac angiosarcoma was diagnosed. The patient received adjuvant chemotherapy and was free of symptoms and recurrence of disease at 14 months follow-up. Due to the fortuitous appearance of clinical signs indicative of stroke, cardiac angiosarcoma was diagnosed and effectively treated at an early, nonmetastatic, and therefore potentially curable stage. Although cardiac angiosarcoma is a rare disease, it should be taken into consideration as a potential cause of cerebral embolic disease.