OBJECTIVE This study was done to ascertain whether three-dimensional echocardiography can facilitate the diagnosis of mitral valve abnormalities. BACKGROUND The value of the additional information provided by three-dimensional echocardiography compared with two-dimensional multiplane transesophageal echocardiography for evaluation of the mitral valve apparatus has not been assessed. METHODS Thirty patients with a variety of mitral valve pathologies (stenosis in 8, insufficiency in 12, prostheses in 10) and 20 subjects with a normal mitral valve were studied. Images were acquired using the rotational technique (ever 2 degrees), with electrocardiographic and respiratory gating. From the three-dimensional data sets, cut planes were selected and presented in both two-dimensional format (anyplane echocardiography) and volume-rendered dynamic display. The data were compared with the original multiplane two-dimensional images. Different features of the mitral valve apparatus were defined and graded by three observers for clarity of visualization and confidence of interpretation as 1) inadequate, 2) sufficient, or 3) excellent. RESULTS All the techniques provided good visualization of the mitral valve (mean global scores +/- SD for multiplane, anyplane and volume-rendered echocardiography were 2.22 +/- 0.34, 2.24 +/- 0.26 and 2.30 +/- 0.25, respectively). With volume-rendered echocardiography, the mitral valve apparatus was scored higher in pathologic than in normal conditions (2.38 +/- 0.24 vs. 2.16 +/- 0.21, p < 0.002). The spatial relationships between the mitral valve and other structures, leaflet mobility, commissures and orifice were scored higher by volume-rendered echocardiography. Prostheses were evaluated equally well by the three methods. Multiplane and anyplane echocardiography were superior for the evaluation of leaflet thickness, subvalvular apparatus and annulus. CONCLUSIONS Transesophageal three-dimensional echocardiography facilitates imaging of some features of the mitral valve apparatus and provides additional information for comprehensive assessment of mitral valve abnormalities.