The correlation between the extent of myocardial fibrosis and subclinical left ventricle (LV) systolic dysfunction in rheumatic mitral stenosis (MS) has not been widely studied. We sought to evaluate the correlation between the extent of LV myocardial fibrosis quantified by late gadolinium enhancement (LGE) using cardiac magnetic resonance (CMR) and global longitudinal strain (GLS) by speckle tracking echocardiography (STE) in patients with rheumatic MS. We prospectively evaluated 36 consecutive rheumatic MS patients who were planning to undergo mitral valve surgery. Then we evaluate the correlation between the extent of LV myocardial fibrosis quantified by LGE CMR and the systolic LV function by GLS using STE. Thirty-six patients with mean age of 45.7 ± 9.9 years old, showed mean LGE was 4.9 ± 2.7%. The mean LV ejection fraction (EF) measured by CMR was 50 ± 10.8%, and the mean LV GLS was 13.5 ± 3.9%. There was a moderate correlation between GLS and LGE (r − 0.432, p = 0.009). There were no correlations between GLS with mitral valve area (MVA) with r 0.149, p = 0.385, mean mitral valve gradient (MVG) with r -0.078, p = 0.653, and LVEF (r 0.299, p = 0.076). There was a moderate correlation between LGE and GLS in patients with rheumatic MS.