Background: Mitral regurgitation increases the volume of the left ventricle and the atrium. Reverse LA remodeling is caused after surgical mitral valve replacement. There have been few studies that look at LA function following MV replacement. LA strain may be used to power LA reservoirs, conduits, and pumps. TMR causes atrial re-modeling in the left ventricle. The use of 3DE enables for more precise and dependable estimation of LA emptying fractions (total, active, and passive). In terms of estimating LA quantities, 3DE is currently more accurate than 2DE. We wanted to look at these issues. Objectives: The current work aimed to evaluate early improvement in left atrial remodeling and function after mitral valve replacement in organic symptomatic mitral regurgitation assessed by three-dimensional echocardiography in Al-Hussein University Hospital. Methods: Prospective 3DE study that was performed on 60 patients with symptomatic chronic organic MR before and after surgery (valve replacement with prosthetic mechanical valve). Additionally, the maximum volume (Vol-max), lowest volume (Vol-min), and pre-contraction volume (Vol-preA) volumes of the LA were computed. Results: Mean age of patients was 48 ± 15 years. Mean BMI reached 26 ± 5 kg/m². Mean systolic blood pressure reached 123 ± 16 mmHg and diastolic blood pressure reached 74 ± 8. Male to female ratio was 1:1 and 51.7% of participants had a previous history of hypertension. Regarding etiology of MR, rheumatic cause was in 33.3% of cases, mitral prolapse was the cause in most of the participants. Regarding 2DE variables of the patients, there was high significant difference between pre- and post-operative results in all variables except for LA total emptying fraction. There was no significant difference in pre and post-operative LA total emptying fraction results. Conclusion: After a successful surgery on the mitral valve, some patients who had an organic MR and intact LV function may have a reversal of LA remodeling and functional alterations. Before surgery, a rise in active atria emptying fraction (AAEF) is linked to an increase in LV relaxation capacity. Preoperative transmitral mean gradient variation and diastolic blood pressure are factors that influence short-term postoperative reverse remodeling of the left atrium in patients.