We investigated whether global longitudinal strain (GLS) is a better predictor of clinical events after surgery for mitral regurgitation (MR) than conventional parameters. The optimal timing for surgery is guided by left ventricular (LV) dimension or left ventricular ejection fraction (LVEF), even though normal LVEF can mask depressed LV systolic function in severe mitral MR. From 2006 to 2016, 506 patients (age 58.5 ± 13.7 years, 54.3% male) with severe primary MR who underwent mitral valve surgery were included. We measured GLS and global circumferential strain. Cardiac events included admission for worsening heart failure (HF), reoperation for failure of MV surgery, and cardiac death. During a median follow-up period of 3.5 years, 56 (11.1%) patients died, 41 (8.1%) were hospitalized for HF, and 10 (2.0%) underwent reoperation. In univariate analysis, LVEF, atrial fibrillation, left atrial dimension, age, previous ischemia, concomitant coronary artery bypass graft, and both GLS and global circumferential strain were predictive of cardiac events. On multivariate Cox models, age (hazard ratio HR: 1.429, 95% confidence interval CI: 1.116 to 1.831; p = 0.005), left atrial dimension (HR: 1.034, 95% CI: 1.006 to 1.063; p = 0.019) and GLS (HR: 1.229, 95% CI: 1.135 to 1.331; p < 0.001) were independent predictors of cardiac events. In subgroup analysis, LV GLS was a significant predictor of cardiac outcome, regardless of the presence of LV dysfunction, the presence of atrial fibrillation, and the type of surgery. Impaired GLS was associated with all-cause mortality (HR: 1.068, 95% CI: 1.003 to 1.136; p = 0.040). GLS appears to be a better predictor of cardiac events all-cause death than conventional parameters. Measuring preoperative GLS is helpful to predict post-operative outcome and determine optimal timing for surgery in patients with severe primary MR. Display omitted