Balloon mitral valvuloplasty (BMV) has been the procedure of choice for patients with significant mitral stenosis. It was suggested that successful BMV reduces the size of the left atrium and improves left atrial function in patients with MS. The purpose of this study was to evaluate long-term effects of BMV on left atrial function. The study included 70 patients with mitral stenosis who underwent BMV 1 year or more before and were coming for routine follow up echocardiography post BMV at Ain-Shams university hospital. Catheterization data and echocardiographic data of the patients before and immediately after BMV were retrospectively collected and compared to the echocardiographic data obtained at the follow up, one year or more after BMV. The mean age of this study group at time of procedure was 34.7 ± 12.08 years. The majority of the study were females representing 75.71% of the cases. BMV resulted in an immediate significant improvement of mitral valve area, mean transmitral pressure gradient and right ventricular systolic pressure with an immediate marked improvement in all LA diameters, areas, volumes and LA function. At the long-term follow up, the results have shown a significant improvement of LA function index (LAFI), LA end systolic volume (LAESV) with the indexed volume (LAESVI) and LA transverse diameter, in comparison to immediately post BMV results. BMV has good immediate and long-term results leading to a significant improvement of LA volumes and function.