Mitral stenosis is a common long-term complication of rheumatic fever and can result in left atrial (LA) enlargement, increasing the risk of thrombus formation. LA thrombi were associated with an increased risk of embolic events such as acute limb ischemia (ALI). ALI occurs when arterial flow to an extremity is abruptly interrupted, which may result in amputation or death. A thrombotic or embolic arterial occlusion is typically the cause of ALI. The authors describe a case of massive thrombus in the left atrium associated with mitral stenosis, which resulted in a systemic thromboembolic complication. A 51-year-old woman with chronic mitral stenosis was hospitalized for palpitation and limb pain without dyspnea or chest pain. Atrial fibrillation was detected via electrocardiography (AF). Echocardiography revealed a rheumatic, thickened, and stenotic mitral valve, as well as a 30 x 24 mm thrombus in the left atrium. She was successfully treated with thrombus removal and mitral valve replacement. Postoperative complications were minimal, and she was discharged from the hospital four days after surgery.