BACKGROUND:Health technology assessment (HTA) should provide an assessment of a technology's effects on health and of the related social, economic, organisational and ethical issues. HTA reports on biosimilars can specifically assess their immunogenicity, their extrapolation to one or more conditions, and the risks of interchangeability and substitution. We aimed to complete a scoping review within the context of HTA organisations to synthesise HTA reports on biosimilars and to map the extension, scope and methodological practices. MAIN BODY:A scoping review methodology was applied. The sources for biosimilars HTA reports were database searches and grey literature from HTA organisation websites up to June 2019. HTA reports of biosimilars were classified as full HTA, mini-HTA or rapid reviews. Data were extracted and recorded on a calibrated predefined data form. We identified 70 HTA reports of biosimilars of 16 biologic products (65.71% in 2015-2018) produced by 13 HTA organisations from 10 countries; 2 full HTAs, 4 mini-HTAs and 64 rapid reviews met the inclusion criteria. Almost all the rapid reviews gave no information regarding any evidence synthesis method and approximately half of the rapid reviews did not appraise the risk of bias of primary studies or the overall quality of evidence. All full-HTAs and mini-HTAs addressed organisational, ethical, social and legal considerations, while these factors were assessed in less than half of the rapid reviews. The immunogenicity and extrapolation of one or more conditions were often considered. The majority of full-HTAs and mini-HTAs contained an assessment of switching and a discussion of an educational approach about biosimilars. No HTA report rejected the adoption/reimbursement of the biosimilar assessed. CONCLUSION:HTA of biosimilars are emerging in the context of HTA organisations and those that exist often duplicate reports of the same biosimilar. Most HTA reports of biosimilars do not conduct a systematic literature review or consider economic issues. No report has rejected the adoption/reimbursement of biosimilars. There is a need to standardise the minimum criteria for the development of HTA on biosimilars to ensure a better understanding and better decision-making.