In the current trial, we will test the efficacy of daclizumab alone in relapsing-remitting MS patients. This trial is a single-centre, open-label, baseline to treatment cross-over phase II trial. Daclizumab will be administered intravenously at 1mg/kg bodyweight. Contrast-enhancing MRI lesions will serve as the primary outcome measure in this phase II trial, and a number of clinical, MRI, and immunological parameters will be measured as secondary and tertiary outcomes. Daclizumab is a promising new immunomodulatory treatment for relapsing-remitting MS.