In the article of O.A.Gorodov, Doctor of Law, Professor of the Chair of Commercial Law of the Saint Petersburg State University (Saint Petersburg, gorodovoleg@gmail.com), the features of the patent monopoly on an invention are investigated. The author proposes to consider the patent monopoly on an invention from two evaluative positions. First, as a necessary legal tool that serves the technical and technological development of the country, and, secondly, as a legal obstacle to the free commercial turnover of goods, works and services