Nicetas of Heraclea (born ca. 1060 ce) was a prolific author of secular andtheological works, including several biblical catenae.1 His catena on John’s Gospel has received little scholarly attention of any kind and has never been edited or published. To begin studying the text, then, one must go directly to the manuscripts containing it; identifying these manuscripts, though, is not a straightforward matter. Consulting the works of Caspar René Gregory, Hermann Freiherr von Soden, and Joseph Reuss yields a combined list of ten manuscripts said to contain Nicetas. Yet out of these ten there are only three manuscripts on which all these scholars agree. The present article examines andcompares these ten manuscripts to determine which of them actually contain Nicetas’s catena of John.