Biosimilars are now a reality in rheumatology. Although analytical and non-clinical procedures to establish similarity have evolved significantly, clinical trials demonstrating equivalent efficacy and safety are absolutely required for all biosimilars. The design of such trials, including equivalence and non-inferiority statistical approaches, are discussed. Clinical evidence on biosimilars that have been approved recently or are presently being developed for use in rheumatology is also reviewed and contrasted with that available for biomimics (or intended copies), which are non-innovator biologics that are marketed in several countries but have not undergone review according to a regulatory pathway for biosimilars. BACKGROUND There is now considerable interest in biosimi-lars among rheumatologists, although the distinction between a true biosimilar and a biomimic (or intended copy) may not be clear to most. Many countries have changed their regulatory requirements to accommodate this new class of medicinal products and to distinguish them from generics. 1 2 Currently, only one biosimilar is approved by the European Medicines Agency (EMA) for the treatment of rheumatological diseases: an infliximab biosi-milar, which is commercialised as Remsima/ Inflectra. Following the lead of the EMA, regulatory agencies in other countries, including South Korea, Canada, Japan, Turkey and Colombia, 3 have approved this infliximab bio-similar. However, the approved indications differ among these countries. For example, EMA allowed the results of clinical trials conducted in rheumatological diseases trials to be extrapolated to inflammatory bowel diseases, while Health Canada did not. 4 Recently, BOW015, an infliximab biosimilar with the commercial name Infimab, 5 and ZRC-3197, an adalimumab biosimilar with the commercial name Exemptia, 6 were approved in India,