The goal of the article is to review the mechanism of action and the use of daclizumab, a humanized monoclonal antibody (mAb) against the alpha subunit of the high affinity interleukin-2 (IL-2) receptor, in the treatment of Multiple Sclerosis (MS). Areas covered: PubMed was searched for the terms 'daclizumab' and 'multiple sclerosis'. The mechanisms of action, pharmacokinetics and pharmacodynamics, major studies, side effects and drug interactions of daclizumab in MS are discussed. Expert commentary: Monthly daclizumab-beta [DAC-beta, formerly daclizumab high yield process (DAC HYP), approved as ZINBRYTA®, which has a different form and structure than an earlier form of daclizumab], is an effective and convenient treatment option for patients with relapsing forms of MS who have failed other treatment, or as a first-line option in highly active MS patients. IL-2 signaling modulation by daclizumab constitutes a novel mechanism of action which may also underlie the adverse and serious adverse events and risk profile of the drug that requires appropriate patient selection, monitoring and risk-mitigation programs.