Background: Large Left atrium (LA) volume has been associated with adverse cardiovascular outcomes in patients with sinus rhythm and atrial fibrillation (AF). Objective: To evaluate the accuracy of left atrial (LA) indexed and non-indexed volume to predict trans-esophageal echocardiographic (TEE) left atrial appendage (LAA) thrombus. Patients and Methods: This was a cross-sectional study which included 30 patients with non-valvular atrial fibrillation (AF) admitted to Cardiology Department or referred to transthoracic and transesophageal echocardiography (TTE and TEE) from outpatient cardiology clinic at Al-Hussien University Hospital, Al-Azhar University, Cairo, Egypt, from February 2020 to October 2020. LA volume was measured on TTE by several methods including LA volume in four and two apical chamber views. All measures were indexed to the body surface area (BSA). Results: There was a statistically significant increase in indexed and non-indexed LA volume in patients with LAA thrombus compared to patients without LAA thrombus. According to ROC curve, the study found that indexed LA biplane volume was predictive for LAA thrombus with with cutoff 52.2 ml/m2 (AUC 0.89, p < 0.007). Conclusion: Large LA volume was suitable to predict LAA thrombus in patients with non- valvular AF.