Background: The development of postoperative left ventricular (LV) dysfunction is a frequent complication in patients with chronic severe mitral regurgitation (MR) and implies a poor prognosis. Assessment of myocardial deformation enables myocardial contractility to be accurately estimated. The aim of this study was to evaluate the predictive value of preoperative regional LV contractile function assessment using two-dimensional echocardiography–based speckle-tracking analysis in patients with chronic severe MR. Methods: Forty-seven consecutive patients with chronic severe MR scheduled for mitral valve replacement were prospectively enrolled. Serial echocardiographic studies were performed before surgery, 6 months and 2 years postoperatively. The LV volumes, stroke volume, and ejection fraction were calculated. Global and regional LS were obtained quantitatively by 2D speckle tracking and automated functioned image (AFI) technique. Results: The patients��� mean age was 58.3짹12.7 years and 20 (41.5%) were male. Preoperative speckle tracking–derived longitudinal strain and strain rate values strongly predicted a postoperative LVEF decrease of >10%. The longitudinal strain at baseline as measured by AFI was the most powerful predictor other parameters such as LVEF and LV volume; the area under the curve was 0.82 and the optimal cut-off value was –0.12. Conclusions: Speckle-tracking echocardiography can be used to predict a decrease in LVEF after mitral valve replacement in patients with chronic severe mitral regurgitation. This promising method could be of use in the clinic when trying to decide upon the optimum time to schedule surgery for such patients. When myocardial deformation begins to decrease, surgery should be contemplated even though patients may show no or only very mild symptoms; this might help prevent irreversible systolic dysfunction in the long term.