Background: The introduction of biosimilar medicines has paved the way for the NHS to make substantial savings. Etanercept biosimilar was launched in February 2016 and provided an opportunity for huge savings to be made for the overall health economy. The drug cost was 30% cheaper than etanercept originator. Methods: Croydon Health Services had 193 rheumatoid arthritis patients eligible for the switch. To date, 25 patients (13%) have not switched for various reasons and 168 patients were switched to the biosimilar. The total saving was over£ 200,000 for Croydon CCG. A monitoring database was set up to follow these patients to ensure safety and efficacy of the new treatment. Results: Of the 168 patients switched, 18 (11%) have switched back to the originator product. The reasons for switchback were lack of efficacy in 11 patients (7%) and intolerance in 7 (4%). The most common intolerances were