Background and objective: The impact of bariatric surgery on sub-clinical alteration of cardiac function assessed using speckle-tracking strain and its relationship with metabolic changes is unknown. We assessed in obese patients with normal left ventricle (LV) systolic function who underwent the biliopancreatic diversion with duodenal switch (BPD-DS); 1) prevalence of subclinical cardiac dysfunction and dyssynchrony in comparison with gender-matched subjects and, 2) the impact of bariatric surgery on myocardial function and its association with changes in NT-proBNP levels and insulin sensitivity. Methods: Prospective, observational study of the effect of BPD-DS after six months on strain, strain rate (SR) and displacement curves using a repeated measures mixed linear regression model analysis. Changes in systolic (LV end-systolic dimension, longitudinal strain) and diastolic (E/A, ESr) parameters were correlated with changes in body mass index (BMI), HOMA and NT-proBNP. Results: Thirty-eight severely obese patients (BMI 48.4±7.4 Kg/m 2 ) had decreased longitudinal strain (-17.0±2.5%) in comparison with 20 patients without obesity (-19.7±1.5%) (p<0.001), which was comparable to controls after surgery (19.3±1.8%) at a mean BMI of 35.7±6 mg/m 2 . Eighteen patients (47%) had a global longitudinal strain considered clinically abnormal. Following surgery, 94% of these patients improved their LV mechanics, with normalization of their global longitudinal strain (p<0.001). Changes in longitudinal strain were not related with changes in NT-proBNP or improvement in insulin sensitivity. Conclusions: There is significant subclinical cardiac dysfunction in patients with severe obesity with normal systolic function. Improvement in longitudinal strain after surgery was not explained by improved insulin sensitivity or changes in NT-proBNP.