Background: Cardiovascular risk stratification in Turner syndrome (TS) is difficult. Increased left ventricular mass associates with an adverse prognosis in several settings, and this study aimed to elucidate this risk marker in relation to metabolic and cardiovascular status in TS. Methods: An echocardiographic follow-up study (4.8 years) of 82 adult females with TS. Left ventricular mass was the primary outcome parameter. Metabolic status (glucose, Hemoglobin A1c, lipids), aortic valve function and morphology, and 24-hour ambulatory blood pressure were secondary outcome parameters. Healthy age-matched females served as baseline controls (n = 55). Results: Left ventricular mass was increased in TS (TS vs. controls: 88 ± 21 g/m2 vs. 77 ± 12 g/m2, P < 0.05). More participants were treated for hypertension at follow-up (32% at baseline vs. 55% at follow-up). This coincided with a reduction of left ventricular mass in TS (84 ± 20 g/m2 at follow up, P < 0.05) and favorable remodeling with a contrasting increase in left atrial size. In a baseline multiple regression model, left ventricular mass (r2= 0.28, P < 0.05) increased with body surface area, age and the presence of a bicuspid aortic valve. In another model, left ventricular mass increased with blood pressure, ongoing estrogen treatment and body surface area (r2= 0.26, P < 0.05). No single factor reached statistically significant levels for prediction of prospective left ventricular mass changes. Conclusion: The increased left ventricular mass in TS was associated with aortic valve disease, age, hypertension, physical stature and metabolic status. During follow-up left ventricular mass was only slightly reduced along with blood pressure, whereas the diastolic dysfunction did not seem to improve.