Rheumatic heart disease (RHD) continues to be one of the leading causes of cardiovascular morbidity and mortality. The mitral valve frequently develops mitral stenosis (MS), and it is the most prevalent valve lesion in patients with chronic RHD. Left atrial (LA) functional impairment is associated with rheumatic MS. The aim of this study was to evaluate the association between LA function and mitral valve area (MVA) in rheumatic MS patients, and to assess the echocardiographic parameters in sinus rhythm and atrial fibrillation (AF) patients. This was a cross-sectional, descriptive study that involved patients with rheumatic MS. Patients underwent a standard 12-lead electrocardiogram and echocardiographic examination. MVA was assessed and correlated with LA function. Comparison was made between sinus rhythm and AF patients. Eighty-one patients with rheumatic MS were included in this study, with 71.6% of them having associated MR. MVA showed a statistically highly significant positive correlation with LA and right ventricular (RV) function, and a statistically significant/highly significant negative correlation with their dimensions. A higher percentage of patients with severe MS was in AF (58.1%). There was a positive correlation between LA function and MVA in rheumatic MS patients. AF was related to the severity of MS.