A 54-year-old woman from Kosovo was admitted to our hospital with dyspnea. On clinical examination, our patient’s blood pressure was 100/60 mmHg, and her pulse rate was 130 beats per minute with a regular rate and rhythm. Cardiac auscultation revealed a diastolic murmur. End-inspiratory crackles suggested pulmonary edema. Two-dimensional transthoracic echocardiography revealed a giant mass originating from her posterior mitral valve leaflet, occupying almost her entire left atrial cavity. Cerebral, thoracic, and abdominal computed tomography was also performed, showing no evidence of additional tumors. Our patient underwent emergency surgical removal of the cardiac tumor. Intraoperative transesophageal echocardiography was performed, which confirmed the presence of the tumor. Our patient underwent bicaval cannulation. Her aorta was clamped and anterograde cardioplegia was administered. Then her left atrium was opened at the interatrial groove. A giant yellowish-white tumoral mass was identified, occupying almost her entire left atrial cavity. The mass had invaded her left superior pulmonary vein and extended into the posterior aspect of her left atrium. The tumor invaded the posterior leaflet of her mitral valve. The tumor mass was carefully detached from the endocardium and then entirely removed, including the posterior leaflet of her mitral valve, which was replaced with a 29-mm St Jude mechanical prosthesis. Macroscopically, the excised lesion was composed of multiple irregular soft tissue fragments. After the surgical excision, the mass was fixed in formalin, paraffin embedded, sectioned at 3-μm thick, and stained conventionally with hematoxylin and eosin. Examination of the histology revealed a high grade sarcoma composed of a fusicellular proliferation in a partial storiform pattern, with irregular fascicles, high cellularity, and pleomorphic and bizarre tumor cells with marked atypia and a high mitotic index. There were also large areas of necrosis. Immunohistochemical examination results were 25 % positive for Ki-67 in the tumor; negative for the muscle markers and the melanocytic markers CD45 and S100; and positive for CD68, vimentin, and alpha-1-antitrypsin. A diagnosis of pleomorphic MFH was made. Our patient’s postoperative course was uneventful. Six weeks after surgery, she started a six-course chemotherapy regimen of 1.5 mg/m2 of ifosfamide on days 1 to 3 and 80 mg/m2 of epidoxorubicin on day 1. The treatment was well tolerated with no unacceptable toxicities. Our patient was still alive with no signs of metastasis six months later.