Background: Measurements of mitral valve area (MVA) are essential to determine the severity of mitral stenosis (MS) and adopt the best management strategies. The aim of the present study was to compare MVA determined by two-dimensional (2D) planimetry to MVA measured by continuity equation (CE) in patients with moderate to severe MS. Methods: We evaluated 73 consecutive patients with the diagnosis of MS scheduled for balloon mitral valvuloplasty or with moderate to severe rheumatic MS admitted at the echocardiography clinic of Imam Khomeini Hospital in 2010. Using 2D images of mitral valve obtained from paraesternal short axis view, 2D planimetry of the mitral orifice area was performed by an experienced cardiologist. MVA by CE was calculated from aortic forward stroke volume divided by transmitral time-velocity integral.Results: The mean value of MVA by 2-D planimetry was 1.0±0.3 cm2. The average values of MVA measured by PHT and CE were 1.0±0.3 cm2 and 0.9±0.4 cm2, respectively. The MVA determined by planimetry correlated well with CE (r=0.832, standard error of estimation [SEE]= 0.166, P<0.001). The mean values of MVA calculated by CE highly correlated with those calculated by 2-D planimetry in patients presenting with both non-significant (r=0.701) and significant (r=0.761) AIs. Conclusion: When planimetry is not feasible, such as in severe calcification of mitral valve or after percutaneous balloon valvuloplasty, CE could be an alternative method for MVA measurement in comparison with PHT.