Although biosimilars have been proven to have equivalent efficacy and no clinically meaningful differences in safety and immunogenicity from their reference products, its use in rheumatology has generated much debate among clinicians, patients, drug manufacturers, and payers. While several of these biopharmaceuticals are still in the pipeline, biosimilars of originators, including adalimumab, etanercept, and infliximab have been approved for the treatment of patients with rheumatic diseases. In this episode, we get further insight into the current state of biosimilars development and adoption in the United States vs other countries, interchangeability among adult and pediatric patients with rheumatologic conditions, nonmedical switching to biosimilars, and an overview of its potential cost benefits for the healthcare system.   Our featured guest is Jonathan Kay, MD, professor of medicine and population and quantitative health sciences, Timothy S. and Elaine L. Peterson Chair in Rheumatology, and director of clinical research, Division of Rheumatology at the University of Massachusetts Medical School in Worcester, Massachusetts.