Background Biosimilars must meet stringent regulatory requirements, both at the time of authorization and during their lifecycle. Yet it has been suggested that divergence in quality attributes over time may lead to clinically meaningful differences between two versions of a biologic. Therefore, this study investigated the batch-to-batch consistency across a range of parameters for released batches of the etanercept biosimilar (SB4) and infliximab biosimilar (SB2). Methods SB4 (Benepali ® ) and SB2 (Flixabi ® ) were both developed by Samsung Bioepis and are manufactured in Europe by Biogen at their facility in Hillerød, Denmark. A total of 120 batches of SB4 and 25 batches of SB2 were assessed for consistency and compliance with specified release parameters, including purity, post-translational glycosylation (SB4 only), protein concentration, and biological activity. Results The protein concentration, purity, tumor necrosis factor-α (TNF-α) binding, and TNF-α neutralization of all batches of SB4 and SB2 were within the strict specification limits set by regulatory agencies, as was the total sialic acid (TSA) content of all batches of SB4. Conclusions Quality attributes of SB4 and SB2 batches showed little variation and were consistently within the rigorous specifications defined by regulatory agencies.As of August 2019, the Biogen Hillerød facility (Denmark) became Fujifilm Diosynth Biotechnologies Denmark ApS, a contract development and manufacturing organization (CDMO) for the manufacture of biosimilars developed by Samsung Bioepis. Key PointsBiosimilars are held to the same rigorous quality standards as any other biologic. SB4 and SB2 biosimilars demonstrated a high degree of batch-to-batch consistency.Quality attributes including purity, percentage of high molecular weight species, tumor necrosis factor-α (TNFα) binding, and TNF-α neutralization remained well within acceptance limits. 2