The measurement of vena contracta is a promising method for quantification of mitral regurgitation (MR). No data exist regarding the ability of power Doppler echocardiography in the assessment of vena contracta in MR. We attempted to clarify the ability of power Doppler in the assessment of vena contracta in MR. The width of vena contracta was measured using power Doppler in 70 patients with chronic MR. Mean effective regurgitant orifice area (EROA) was calculated quantitatively by the spectral Doppler. The area of vena contracta was calculated by measuring the width of vena contracta from the following formula: Vena contracta area = p* (vena contracta width/2) 2 . The width of vena contracta ranged from 3.6 to 8.4 mm. The EROA varied from 0.10 to 0.56 cm 2 . Good correlations were found between EROA and vena contracta area obtained by power Doppler (r = .95, p < .0001, SEE = 0.04 cm 2 ). Strong relationships were observed between the area of vena contracta and regurgitant volume (r = 0.93, p < .0001, SEE = 8.1 ml/ beat), and regurgitant fraction (r = 0.95, SEE = 6.1%). Power Doppler may provide an additional method for assessing vena contracta in MR.