The analysis of valvular morphology is important in selecting patients with mitral rheumatic stenosis for percutaneous mitral valvuloplasty. Transthoracic echocardiography definitely plays a major role in this characterization whereas the usefulness of transesophageal echocardiography has not been determined yet. We studied 95 patients (82 females, 13 males, mean age 51 +/- 12 years) undergoing mitral valvuloplasty (Inoue's technique). The two methods were compared for: morphologic mitral score; correlation between score and increase in mitral valve area; ability to predict post valvuloplasty mitral regurgitation; accuracy in detecting atrial thrombosis. A significant linear correlation between transthoracic and transesophageal echocardiographic scores was observed (r = 0.78, p < 0.001). Transesophageal echocardiographic score was significantly lower (6.8 +/- 1.62 versus 7.17 +/- 1.69, p < 0.05) due to a lower estimation of the extent of calcifications (0.7 +/- 0.97 versus 1 +/- 1.12, p < 0.05). Correlation coefficients between increase in mitral valve area and scores obtained with the two methods were similar (0.29 and 0.30). For both echocardiographic techniques 6 was the best cut-off score value. None of the clinical, hemodynamic and echocardiographic variables was able to predict the occurrence of severe mitral regurgitation. Five patients with atrial thrombosis were identified by transesophageal echocardiography but only 1 by transthoracic echocardiography. We conclude that the two echocardiographic methods have complementary roles in the evaluation of patients undergoing mitral balloon valvuloplasty. Mitral valve morphologic score can generally be assessed adequately by transthoracic echocardiography but transesophageal echocardiography is mandatory in order to exclude left atrial thrombi. The occurrence of post valvuloplasty severe mitral regurgitation cannot be reasonably predicted on echocardiographic basis.