The limitations of 2-dimensional and pulsed Doppler echocardiography in patients undergoing mitral valvuloplasty are well known. This study was undertaken to assess the value of color Doppler flow imaging in 36 symptomatic mitral stenosis patients who subsequently underwent successful balloon mitral valvuloplasty by comparing the results to those obtained at cardiac catheterization. Color Doppler-guided conventional Doppler assessment agreed well with cardiac catheterization results in classifying mitral stenosis as mild, moderately severe and severe, both before and after valvuloplasty. Color Doppler was also useful in identifying patients who had moderate to severe mitral regurgitation before and after valvuloplasty. Color Doppler flow mapping was more sensitive than oximetry in the detection of iatrogenic atrial septal defects, which were noted in 25 patients. The defects of those patients with smaller defects by color Doppler (diameter less than 0.7 cm) or echocardiographic shunt volume less than 0.7 liters/min tended to close, usually within 6 months, as opposed to those with larger defects or higher shunt volumes, which tended to persist. Echocardiographic shunt volumes revealed a fair correlation with oximetric results.