Published among the posthumous Opuscula of Isaac Barrow in 1687, the Epitome fidei et religionis Turcicae offers an exposition of the main tenets and practices of Islam that is unusually accurate for its time. The Epitome has been noted in passing by Barrow’s biographers and by scholars of seventeenth-century Oriental studies; but it is here firmly identified as the work of the Polish-born Ottoman dragoman and musician Ali Ufki, known in Latin as Albertus Bobovius (Wojciech Bobowski). As the Epitome has never before been studied in detail, this article considers its nature, its importance and its circulation in the European Republic of Letters. The first part treats the evidence of Barrow’s amateur interest in Oriental studies, including his acquisition of the Epitome, and establishes Ufki’s authorship of the treatise. The second part examines the Epitome itself and traces its dissemination and influence through such figures as John Worthington, Samuel Hartlib, William Sancroft, Claes Rålamb and Johan Ulrich von Wallich.