My consideration of the historical opera I Medici is based on the analysis of the piece’s dramaturgy. In my opinion, libretto is a key to understanding any operatic dramas; it constitutes their primary foundation on which subsequent semantic layers of this naturally syncretic musical genre are being formed. Therefore, in my paper I have analysed individual components of the libretto, with a special emphasis placed on the characters, their personality traits as well as their musical representation in Leoncavallo’s work. Analytical operations concerning dramaturgic aspects of the opera are an essential first step in consideration of the musical layer, which lies at the heart of my research. In my paper, I follow the path marked out by a musicologist Luca Zoppelli; however, his work is only a starting point for a more detailed study of the opera’s expression and the procedures used in musical representation of veristic ideas. Verity – not only in historical sense – becomes a leading category which unifies the opera at every level: from its original source recorded in the chronicles to composer’s embodiment of the story.