Tumor necrosis factor-alpha (TNF-⍺) antagonists are biological drugs with multiple authorized biosimilars. Biosimilars are becoming critical to the financial sustainability of health systems. Recent studies emphasize that physicians' knowledge regarding biosimilars has not yet progressed sufficiently to overcome their concerns regarding biosimilars' safety and efficacy. To assess the current knowledge, opinions, and attitudes toward TNF-⍺ antagonist biosimilars among postgraduate physicians and specialists, an anonymous, self-administered survey was implemented on SurveyMonkey between February and May 2022. The survey was validated through think-aloud interviews with senior and postgraduate physicians in rheumatology, gastroenterology, and immunoallergology, and a senior epidemiologist. Participant recruitment was conducted with the help of the physicians' professional societies and departmental head physicians of two university hospitals in Western Switzerland. Most physicians felt more comfortable initiating a TNF-⍺ antagonist biosimilar in biologic-naive patients (BNPs) than switching patients stabilized on the original biologic (originator). However, most participants agreed that BNPs should start treatment with the biosimilar rather than the originator when available. Postgraduate physicians and specialists in rheumatology, gastroenterology, and immunoallergology who participated in this survey were familiar with TNF-⍺ antagonist biosimilars and were confident in prescribing them. Yet, they still preferred to avoid switching a patient already on the originator.