Available treatment options for relapsing-remitting multiple sclerosis (MS) have expanded in recent years, and several injectable therapies are under development. In this Rapid Review, we summarise emerging injectable therapies for relapsing-remitting MS, and discuss pharmacological mechanisms, clinical trials, adverse events, and use in clinical practice. Many new potential treatments for MS are at an intermediate to advanced stage of development. Alemtuzumab is a monoclonal antibody that has shown efficacy in phase 3 trials but, because of serious adverse events associated with this drug, clinical monitoring is essential. Pegylated interferon beta-1a has shown efficacy in a phase 3 trial. Daclizumab and ocrelizumab are monoclonal antibodies that have shown efficacy and acceptable safety profiles in phase 2 trials; both are under investigation in ongoing phase 3 trials. Ofatumumab is a monoclonal antibody that has shown efficacy in a small phase 2 trial. Animal models suggest that anti-LINGO1 antibody has remyelinating potential, and phase 2 trials of the antibody are underway. Further clarification of purported mechanisms of action and continued surveillance will be essential to establish the safety and clinical efficacy of these drugs in patients with relapsing-remitting MS.