Background: Left ventricular (LV) function can be masked in patients with chronic LV volume overload. We evaluate the availability of N-terminal pro B type natriuretic peptide (NT-pro BNP) and Tei-index in predicting postoperative LV function and in-hospital events (IHE) in patients with chronic severe mitral or aortic regurgitation (MR or AR). Methods: Forty three patients (55.6짹15.2 years old, 24 females, 25 MR) with severe MR or AR who underwent valve surgery were enrolled. LV ejection fraction or time required for hospital stay and IHE were analyzed. Results: At baseline, the level of NT-pro BNP was 1304.4짹1967.4 pg/ml, LV ejection fraction (EF) was 57.9짹15.5 %, and Tei-index was 0.52짹0.13. NT-pro BNP was significantly correlated with Tei-index (r=0.46), but not with LVEF (r=-0.28). LVEF and Tei-index following valve surgery were 54.7짹11.1 % and 0.65짹0.19. Tei-index was significantly increased following valve surgery (0.52짹0.13 to 0.65짹0.19, p < 0.001). NT-pro BNP was significantly correlated with postoperative LVEF (r=-0.48) and Tei-index (r=0.61). Baseline Tei-index was also significantly correlated with postoperative LVEF (r=-0.67) and Tei-index (r=0.72). Only the level of NT-pro BNP was significantly associated with IHE (827.7짹1644.7 vs. 2925.2짹2291.5 pg/ml, p= 0.03). The duration of in-hospital stay was significantly correlated with NT-pro BNP (r=0.74), postoperative LVEF (r=-0.45), and postoperative Tei-index (r=0.43). Conclusion: NT-pro BNP and Tei-index before valve surgery were very useful for the post-operative risk stratification and could predict postoperative LV function and IHE in patients with chronic severe MR or AR.