There are several ancient Roman and Byzantine gold coins in the collection of the Ossolineum. Some of them have different marks on their surface, including lines and marks that can be interpreted as letters. Apart from single letters, there are examples of longer inscriptions, perhaps names. I propose to present a wider perspective on the phenomenon of graffiti on coins and present the results of my studies regarding the history of these coins. I explore the reasons for the presence of a relatively large number of coins in the Ossolineum's collection with such marks and invite a discussion of this problem with the participants of the session.