Percutaneous Balloon mitral valvuloplasty (PBMV) has emerged as the treatment of choice for selected patients with severe rheumatic mitral stenosis. Our aim of the study is to evaluate the possibility of the mitral leaflet separation (MLS) index as an echocardiographic parameter in aiding successful PBMV and to evaluate its reliability in assessing the morphology and hemodynamic of mitral valve in pre and post mitral valvuloplasty (PBMV). MATERIALS AND METHODS: This is a single centre, observational study of twenty six patients suffering from symptomatic moderate to severe MS who underwent PBMV at Rajiv Gandhi government general hospital, Chennai in cardiology department from January 2018 to June 2018. RESULTS: MVA increased from 0.86 ± 0.12 to 1.72 ± 0.21 cm2 (P=0.02) using 2D planimetry. MVA increased from 0.92± 0.13 to 1.78± 0.22 cm2 (P= 0.02) by pressure half time method (PHT) .MLS index had good correlation with MVA by PHT pre (r=0.92) and post (r=0.81) PMBV (p=0.0001) .MLS index had strong correlation with MVA using 2D Planimetry pre (r=0.92) and post PBMV (r=0.89) (p=0.0001) MLS index had weaker correlation with mean LA pressure pre (r=0.003) and post PBMV (r=0.239) (p=0.98). CONCLUSION: MLS demonstrated a very good correlation with MVA measured with 2D planimetry and PHT methods and is very easy to obtain in the hands of the inexperienced and in special setting like Cath lab. It can be used as an important parameter for assessing the success of percutaneous mitral balloon valvuloplasty.