Randomized placebo-controlled clinical trials have been considered the most rigorous method of evaluating the efficacy of novel treatment interventions. The first effective disease-modifying therapies (DMTs) for relapsing-remitting multiple sclerosis (RRMS) were approved in the 1990s after a number of pivotal placebo-controlled trials. Since then, the ethics of the continued use of placebo in clinical trials of new DMTs for RRMS has been the subject of repeated policy statements and recommendations by international committees. As further data have accumulated demonstrating a reduction in long-term morbidity and mortality with early initiation of DMT, a growing consensus has emerged that further inclusion of placebo arms in clinical trials of novel RRMS therapies is no longer ethical.