Abstract Background The effect of pectus excavatum (PE) on cardiac morphology and function has been reported previously. The right heart chamber size and cardiac output improved after the surgical correction of PE. However, the effect on the mitral and tricuspid valve has not been investigated. Purpose Our purpose was to investigate the morphological changes in the tricuspid and mitral valve after PE surgery. Methods We enrolled 25 patients who underwent Nuss surgery for PE repair. The inclusion criteria were 1) aged 15 years or older, 2) Haller Index of more than 5.0, and 3) transesophageal echocardiography (TEE) during PE surgery. We measured RV size and the sphericity index of tricuspid and mitral valve using 3D echocardiography before and after the elevation of the sternum. The sphericity index was calculated as the ratio of anterior-posterior (AP)/medial-lateral (ML) dimeter for the mitral valve (MV) and septal-lateral (SL) / AP dimeter for the tricuspid valve (TV). Results Mean age was 26±11 years, and 28% was female. The Haller index was 6.9 ± 2.8. All patients had normal left ventricular and right ventricular function evaluated with transthoracic echocardiography. The chamber diameter of the base and mid in RV increased after the elevation of the chest. The AP and SL dimeter were enlarged after the elevation of the chest in the TV, and the sphericity index of TV did not change. On the other hand, AP diameter increased but ML diameter was constant in the MV, and the sphericity index of MV increased after the elevation of the chest. Therefore, the annulus size was increased but the morphology was not changed in the TV. Unlike the TV, the morphology of MV annulus became close to circular from flat shape. In several patients, trivial mitral regurgitation was observed after elevation of chest, and possibly affected by the morphological change of the MV annulus. Conclusions The surgical repair for pectus excavatum effected not only right ventricular morphology but also on the tricuspid and mitral valve. The annulus change was different between the tricuspid and mitral valve.