In his Vita sancti Patricii, written in the late seventh century, Muirch depicts St. Patrick, the national apostle of Ireland who lived in the fifth century, with a number of interesting characteristics. In this paper I shall demonstrate that the sources behind Muirch's account of Patrick included biographies of New Testament apostles. These biographies provide a background in religious literature for some of the events which, according to Muirch, befall Patrick on his missionary journey around the island of Ireland.