Summary Atrial fibrillation (AF) is the most common sustained arrhythmia in the general population; its prevalence increases with age and is generally associated with increased mortality. The analysis of left atrial (LA) strain is a new tool that can be used to evaluate LA function. So, this study aimed at assessing LA function using tissue Doppler and studing its correlation with the CHA 2 DS 2 -VASc score. This study included 100 patients with persistent nonvalvularAF (group I) referred to the Cardiology Department, Benha University Hospital and were compared with 100 control patients of sinus rhythm (group II) of matched age and gender. . They were assessed for baseline characteristics, admission data, electrocardiography and echocardiography. • The current study concluded that there was no significant statistical difference between the 2 groups as regarding the age (p value =0.16) and sex (p value =0.32). • DM&HTN were more prevalent in patients of group I (p value < 0.001). • Past history of stroke, heart failure and peripheral vascular disease were significantly increased in patients of group I (p value 0.05). • LA volumes and dimensions were significantly increased in patients of group I (p value