Background: Cardiovascular side effects such as bradycardia and atrioventricular block were observed during the early clinical trials of fingolimod in multiple sclerosis, and one cardiovascular- linked death has been reported in the post-marketing period. Objective: To investigate the medium-term effects of fingolimod on heart function in order to obtain further insights into its cardiac safety profile. Methods: The study involved 53 patients starting treatment with fingolimod 0.5 mg daily and 25 patients treated with natalizumab 300 mg monthly. Cardiac function was assessed by means of echocardiography at baseline (T0), and after one (T1), six (T6), and (in the case of the fingolimod group) 12 months (T12). Results: Mean left ventricular ejection fraction significantly decreased and end-systolic volume increased from T0 to T1 ( p=0.005) and T6 ( p=0.0001) in the fingolimod but not the natalizumab group, although a slight increase was observed at T12. A similar decrease in ejection fraction was also observed after six months in nine patients switched from natalizumab to fingolimod. Conclusion: Fingolimod significantly reduces left ventricular systolic function in MS patients. This effect has no clinical consequences in subjects without previous cardiac disorders, but suggests that more caution is required in patients with current or previous heart failure.