AbstractPatients with rheumatic mitral stenosis (MS) often present complications such as atrial fibrillation and thrombus formation with significant morbi-mortality. Rarely, a free-floating ‘ball thrombus’ is found with possible catastrophic outcomes. We describe three cases of documented left atrial ‘ping-pong’ shaped ‘thrombus ball’ within MS: a 51 year old presented with acute heart failure with a fatal outcome due to the huge round thrombus closing the tight mitral valve, a 67-year-old and a 68-year-old male who were both urgently rushed to the operating room after accidental finding. The surgery was successful and consisted on mitral valve repair and thrombectomy. Our aim is to show that gigantic unattached thrombus ball within neglected rheumatism MS is a rare life-threatening entity, thus highlighting the importance of early diagnosis of such conditions present in endemic countries. A prompt surgery should be considered to avoid an eventual embolization and sudden death.