The European Medicines Agency's recent approval of biosimilars and their sudden appearance on the market will revolutionize the way physicians treat the severe conditions for which biologics have had a major impact. In the field of rheumatology, these agents are especially important because most new treatments are based on this kind of medication and because patents on the original drugs are expiring. To use these new medications, the treating physician must read and understand the clinical trials related to biosimilars. These studies are not the typical superiority trials in which new agents are compared with standard treatment; rather, they evaluate different formulas to determine whether they are no better or worse. This article summarizes the clinical aspects of drug development with regard to the efficacy and safety of these new medications.