History of Science and Engineering Annotation << Back History of Studying the Blood-Brain Barrier: Achievements and Mistakes Shuvalova M.L. The blood-brain barrier (BBB) is a structure that regulates the exchange of substances between the blood and the brain. A careful analysis of the literature shows that many concepts regarding the BBB are incorrect. The introduction of the concept of the brain's vascular barrier is often attributed to Ehrlich, but he did not acknowledge that the permeability of brain vessels differs from that of other organs. The term "blood-brain barrier" is often attributed to Lewandowsky, but it does not appear in his works. The fi rst to use this term was Stern in the early 1920s. There is also a belief that in embryos and newborns, the BBB is more permeable than in adult animals. This has weak experimental evidence, which is often misinterpreted and cited. Misunderstanding the nature of the BBB negatively affects its study, hinders research on related diseases, and complicates the search for drugs to treat its disorders. This paper provides a historical overview of BBB research from the 17th century to the present day, examines cases of errors and misinterpretation of experiments, and describes the modern understanding of what the BBB is (not). Keywords: Blood-brain barrier, BBB, Stern, microvessels. DOI: 10.25791/intstg.12.2023.1456 Pp. 29-35.