Motivation: Assessing EuroSCORE II and STS score values as predictors for postoperative morbidity and mortality in patients undergoing minimally invasive heart valve surgery.Methods: Retrospective cohort study of 273 consecutive patients since November 2010 and November 2014.EuroSCORE II and STS score values were collected for all of them.Discrimination was measured with the area under the ROC curve and calibration was assessed by means of the Hosmer-Lemeshow test (HL).Results: Discrimination was similar for both tests, EuroSCORE II showed an area under the ROC curve of 0.68 (CI 95%: 0.512-0.856),p = 0.039 and STS score was 0.650 (IC 95%: 0.453-0.848),p = 0.107.Calibration power for general mortality was p = 0.28 for EuroSCORE II and p = 0.27 for STS.Both scores underestimated mortality risks.Morbidity and mortality were higher when the minimally invasive technique was implemented and it was gradually reduced to 1.4% (n = 1) by the fourth year of the study.Conclusions: Predictive value of EuroSCORE II and STS was similar.Development and validation of local scales would help improve risk stratification within our population group and truly reflect our clinical practice.Collaborative studies with larger sample sizes are required in order to estimate the usefulness of the available scales and to suggest a scale of its own for this type of surgery.