Multi-center, rater-blinded, parallel-group, two arm, randomized study. Patients with relapsing-remitting forms of MS, respecting all inclusion/exclusion criteria, will be randomized into two equal-size parallel arms after three months of treatment with Interferon-beta-1b, receiving Atorvastatin 40mg/d or not. Enrolment of 80 patients (1/2 in the Atorvastatin group) is planned. Patients providing written informed consent will be treated for 15 months.