Objective: The purpose of this study was to determine the feasibility and significance of the proximal isovelocity surface area (PISA) method in children with rheumatic mitral regurgitation (MR). Methods: Thirty-one children (mean age 12.3±3.1 years), with chronic MR, were evaluated by semiquantitative and quantitative Doppler, quantitative two-dimensional echocardiography and the PISA methods. Also, we compared the effective regurgitant orifice area, regurgitation volume and systolic left ventricular functions in mild-moderate and severe MR. Results: There were no statistically significant differences in the regurgitant orifice area and regurgitant volume values obtained by the PISA method and the quantitative Doppler (p>0.05) but they were different from the same values obtained by two dimensional echocardiography (p<0.05). There were excellent correlations between the regurgitant orifice area, regurgitant volume and the radius of the proximal flow convergence hemisphere (r=0.882, r=0.925, r=0.880; p<0.05). We found a very good correlation between the regurgitant orifice area obtained by the PISA and left ventricular end-diastolic diameters, the ratio of the jet/left atrial area, grading with color Doppler imaging (r=0.763, r=0.745, r=0.618; p<0.05). Conclusion: It is concluded that MR can be accurately predicted in children by using the PISA method as like as the Doppler method.