This article describes comprehensive conservation works and examinations carried out on the late-Gothic painting “Annunciation to the Blessed Virgin Mary” from the Kórnik Library of PAN [the Polish Academy of Arts and Sciences] from 2013 until 2014. The painting underwent conservation several times in the 19th and 20th centuries. A detailed analysis of the state of preservation of the work, determination of the causes of its damage, and the chemical composition of the particular technological layers with the help of such examination methods as laboratory analyses of the pigments and binders, and UV and IR analysis of the painting, made it possible for the researchers to identify and remove all the secondary layers and to restore the work in such a way as to recover its original aesthetic value and technological properties.