Objective: Closed repair of pectus excavatum (PE), also known as the NUSS procedure, has become more popular recently, and whether this operation results ill true cardiac improvement as opposed to postoperative physical rehabilitation or a psychological effect deserves examination. Methods: Ten PE patients (8 males, 2 females) aged 4 to 54 years (average, 19.6 +/- 14 years) were prospectively evaluated using preoperative computed tomography (CT) scan, Pulmonary function studies, electrocardiogram and transthoracic echocardiographic (TTE) evaluation of cardiac function. The same studies were repeated at 3 months post bar placement. In addition, intraoperative transesophageal echocardiogram (TEE) was done to Measure the procedure-related values of the cardiac chamber and functional indices before and after turning of the pectus bar. Results: Statistically significant changes in the pectus index, obtained by dividing the internal transverse distance of the thorax by the vertebral-sternal distance at the most depressed portion of the deformity, were noted after Surgery, decreasing from 5.06 +/- 1.46 to 3.55 +/- 0.48 (p < 0.05). Most patients with previously abnormal electrocardiograms showed a normal pattern after surgical repair (p < 0.05). Five Subjects in the PE group (50%) showed mitral valve prolapse in TTE and 4 of them had mitral regurgitation. However, these valve patterns could not be corrected after Surgical repair of the chest wall deformity (p=0.25). The cardiac chamber and the function of the right ventricle were evaluated by intraoperative TEE and showed significantly increased values after retrosternal dissection and post-turning of the pectus bat. Conclusion: The data of this study supports the concept that closed repair directly contributes to hemodynamic improvement.