Abstract: AIM:To determine the relationship between histories, left atrium and ventricle diameters, left ventricular ejection fraction (LVEF), thrombus formation, blood coagulation parameters and high sensitive Creactive protein (HsCRP). METHODS: According to the results of transesophageal echocardiography (TEE) examinations, data of 52 patients with cardiac thrombus formation were analyzed retrospectively. RESULTS: Of the 52 patients, 34 were male (654%) and 18 female (346%). Thirty one patients (654%) were in NYHA Class III or higher. Atrial fibrillation (AF) was the top complication followed by ischemic brain disease, hypertension and coronary heart disease. Altogether, 70 emboli were found and in 20 patients thrombus formations were in the atrial appendage. A significant difference was observed in gender, left atrium and ventricle diameters, and HsCRP (P<005). CONCLUSION: AF is one of the most important factors for cardiac thrombus formation. Left atrial appendage is a common site for thrombus formation. TEE is an optimal way to detect cardiac thrombus formation.