Objective: To evaluate the efficacy and safety of CT-P10, a rituximab biosimilar after a single switch, during a multinational, randomized, double-blind Phase 3 trial involving patients with RA. Methods: Patients received 48 weeks' treatment with CT-P10 or United States- or European Union-sourced reference rituximab (US-RTX and EU-RTX, respectively). Patients entering the extension period (weeks 48-72) remained on CT-P10 (CT-P10/CT-P10; n = 122) or US-RTX (US-RTX/US-RTX; n = 64), or switched to CT-P10 from US-RTX (US-RTX/CT-P10; n = 62) or EU-RTX (EU-RTX/CT-P10; n = 47) for an additional course. Efficacy endpoints included Disease Activity Score using 28 joints (DAS28), American College of Rheumatology (ACR) response rates, and quality of life-related parameters. Pharmacodynamics, immunogenicity and safety were also assessed. Results: At week 72, similar improvements were observed by disease activity parameters including DAS28 and ACR response rate in the four extension period treatment groups. Quality of life improvements at week 72 vs baseline were similarly shown during the extension period in all groups. Newly developed anti-drug antibodies were detected in two patients following study drug infusion in the extension period. Similar pharmacodynamic and safety profiles were observed across groups. Conclusion: Long-term use of CT-P10 up to 72 weeks was effective and well tolerated. Furthermore, switching from reference rituximab to CT-P10 in RA was well tolerated and did not result in any clinically meaningful differences in terms of efficacy, pharmacodynamics, immunogenicity and safety. Trail registration: ClinicalTrials.gov, http://clinicaltrials.gov, NCT02149121.