History of Science and Engineering Annotation << Back THE ORIGIN OF THE BEGINNING OF THE BETA-FUNCTION THEORY IN THE WORKS OF L. EYLER I.V. Ignatushina, O.B. Polischuk This article is devoted to the work of Leonard Euler on the theory of special functions. In addition to his published works, which dealt with the theory of the B-function, Euler’s correspondence with scientists and unpublished materials from his notebooks concerning this theory were involved in the study. This makes it possible to trace the train of thought of the great scientist in the development of a mathematical theory and to find out when and when solving what problems Euler came to the necessity of introducing this function. Keywords: Beta function and its properties, history of special functions, L. Euler. DOI: 10.25791/intstg.3.2021.1258 Pp. 03-10.