Background: Remodeling of the left atrium (LA)is a reflection of chronicity of the underlying, often occult cardiovascular disease. The presence of left atrial enlargement indicates clinically significant risk of adverse cardiovascular consequences for the patient. Left atrial volume provides a more sensitive assessment of left atrial enlargement, which is an important predictor of AF, providing incremental information beyond that afforded by the clinical risk factors and conventional M mode LA dimension. Objective: Assessment of left atrial volume as a parameter of ventricular function in patients with non-valvular atrial fibrillation. Patients and methods: The study was conducted on convenient sample of 50 patients with non-valvular AF and 50 normal control group who presented to Damietta Cardiology Center Outpatient Echocardiography Laboratory for a resting transthoracic study.The eligible patients were adults aged from 26 to 67 years, who had no history of pacemaker implantation, valvular heart disease (except mild degree), congenital heart disease and ischemic or dilated cardiomyopathy. Results: our study revealed that there was a strong direct significant graded relationship between the severity of diastolic dysfunction and left atrial volume index (LAVI) in patients of non-valvular AF. There was limited significance regarding Tei index and global longitudinal strain (GLS). Therefore, LAVI can be considered a sensitive and specific echocardiographic indicator for left ventricular diastolic dysfunction. We can consider LAVI the A1c of the heart. Conclusion: Diastolic dysfunction in non-valvular AF patient can be assessed using LAVI with limited significance of Tei index and GLS. Regarding systolic function in those patients, it can be assessed using GLS as it is considered sensitive index of early systolic dysfunction.