We studied intraobserver (n = 24), interobserver (n = 24) and interexperiment (n = 12) reproducibility of left ventricular (LV) mass and volume measurements in mice using an 11.7 T MRI system. The LV systolic function was assessed with a short-axis FLASH-cine sequence in 29 mice, including animals having undergone transverse aortic constriction. Bland-Altman and regression analysis were used to compare the different data sets. Reproducibility was excellent for the LV mass and end-diastolic volume (coefficient of variability (CoV) between 5.4 and 11.8 %), good for end-systolic volume (CoV 15.2–19.4 %) and moderate for stroke volume and ejection fraction (CoV 14.7–20.9 %). We found an excellent correlation between LV mass determined by MRI and ex vivo morphometric data (r = 0.92). In conclusion, LV systolic function can be assessed on an 11.7 T MRI scanner with high reproducibility for most parameters, as needed in longitudinal studies. However, data should be interpreted taking into account the moderate reproducibility of small volumes.