For the first time, the bryological flora of the Vatican City State has been studied. Research concentrated in particular in the area of the Vatican Gardens, and led to the identification of 121 taxa of bryophytes (14 liverworts and 107 mosses), among which one liverwort and nine moss species are new reports for the Lazio Region. Particularly interesting among these species is the presence of Tortula bolanderi (Lesq. & James) M. Howe, the first report for the Italian peninsula. The study is of considerable floristic and biogeographical importance, and contributes significantly to the knowledge of a territory that until now had been unexplored from the bryological point of view.