Restoration is one of the most important areas in preserving the world’s cultural heritage. The 19th century is a landmark in the history of restoration. At that time, it turned from a private practice of self-taught artists into a real scientifically based discipline. Many European countries have faced the problems of cultural heritage preservation, and everywhere they were solved in different ways, depending on local peculiarities and experience. This article deals with previously unknown facts from the life and activity of the first Russian restorer Andrei Filippovich Mitrokhin, who was born and studied painting in the town of Toropets. He served as a simple soldier, then on duty he ended up in Saint Petersburg, where he was soon granted a valet at the Hermitage. His career developed under Franz Ivanovich Labensky, who assumed the position of chief curator of paintings in the Hermitage Gallery in 1797. Mitrokhin’s role in the history of Russian restoration and, in particular, the Hermitage cannot be overestimated. He not only restored paintings and trained several apprentices, but also worked independently on the development of new methods of restoring paintings. By mastering new techniques and methods of mechanical restoration, Mitrokhin and his students managed to preserve more than a thousand paintings from the Hermitage collection, many of which are painting masterpieces. Unfortunately, some aspects of Mitrokhin’s biography, especially his life outside the Hermitage, have long been overlooked by scholars. This paper examines the problem of his alleged date of birth, family and friendship ties, etc. The archival data cited by the author allow us to take a fresh look at Mitrokhin as a restorer, and also shed light on some socio-cultural aspects of his time.