Reconstruction surgery of the mitral valve has become an alternative to mitral replacement in patients with pure mitral regurgitation. Preoperative assessment of the anatomic and functional aspects of the valvular lesion is of the utmost importance in conservative surgery. Transesophageal echocardiography is a new approach to investigating the mitral valve, and our study was undertaken with the purpose of determining its importance in the exploration of mitral regurgitation of non-rheumatic origin. Subjects included were twenty patients with pure and isolated mitral regurgitation (MR): 14 males and 6 females with an average age of 47 +/- 13 years. All the patients underwent a first transesophageal 2D and color Doppler echocardiographic examination, and 5 of them underwent a second one during cardiovascular surgery. Mitral anulus diameter, mitral valve cordae tendinae status, valvular leaflet length and coaptation were examined and color Doppler regurgitation jet area was measured. Mitral anulus diameter was 40.2 +/- 8.06 mm (diastolic) and 41.9 +/- 8.53 mm (systolic) and was above the values considered to be normal. Anterior leaflet length was 30.8 +/- 3.12 mm and posterior leaflet length was 22.9 +/- 4.74 mm; regurgitation jet area was between 1.2 cm2 and 13.52 cm2 with an average of 5.44 cm2. In the group with MR of mixomatous origin, systolic anulus diameter showed a linear correlation with regurgitation jet area (r = 0.79). In the 6 patients who underwent cardiac catheterization, angiographic semiquantitative evaluation of the MR confirmed that based on color Doppler jet area. In all twenty patients transesophageal echocardiography enabled us to identify the mechanism responsible for mitral insufficiency.(ABSTRACT TRUNCATED AT 250 WORDS)