The article considers the use of the Russian language as the state language in medicine and healthcare. A circumstance requiring linguistic accuracy is that medical documents, if necessary, serve not only medical, but also legal purposes. Based on their previous publications and new research, the authors show that in medicine and healthcare there is no single consistent and equally understood lexicon by all interested parties, which complicates scientific and educational activities in the medical field, creates certain difficulties in the research of forensic medical experts in the production of expert actions. One of the reasons is that medicine, developing, naturally goes beyond the old theories, explains the mechanisms of diseases in a new way, and the established terms remain old, based on an outdated theory. In this article, the authors discuss the problems of the functioning of the Russian language as the state language in medicine and in healthcare, mainly in relation to various medical documents (medical histories, medical records, medical and legal documents related to cases of medical errors, assessments of the legal capacity of the subject, etc.). Examples of ambiguous and inaccurate use of biomedical terms in various official documents are given. The arguments in favor of creating a normative explanatory dictionary of medical terms as part of the state language of Russia are presented. This will contribute to unified approaches in the interpretation of complex issues of medical activity and scientific research in medicine related to professional discrepancies.