This manuscript preserves one of the most famous medieval Arabic medical treatises, the Kitab al-Mansouri fi al-Tibb (The book on medicine dedicated to al-Mansur), which was composed by the well-known Persian physician, natural scientist, philosopher, and alchemist Abu Bakr Muḥammad ibn Zakariya al-Razi (865–925) early in the 10th century. As apparent in the title of the book, this work is dedicated to the governor of the province of Rayy (in present-day Iran and the birthplace of al-Razi), Al-Mansur ibn Ishāq. Al-Razi (also known by Latinized versions of his name, Rhazes or Rasis) lived in Rayy for at least 30 years and became director of its hospital. He later moved to Baghdad, capital city of the Abbasid caliphate, where he directed the famous local hospital and composed an impressive number of medical, philosophical, and alchemical works. The Kitab al-Mansouri is one of his two most influential books, the other being the extensive medical encyclopedia Kitāb al-Hāwī fī al-Tibb (The comprehensive book on medicine), which gained fame in the West under the Latin name Liber Continens. The content of the 10 chapters of the Kitab al-Mansouri is both theoretical and practical and is organized as follows: chapters one to six deal with diet, hygiene, anatomy, physiology, general pathology, and surgery, subjects that were somehow considered as mainly theoretical by the author. The last four chapters of the treatise are devoted to more practical aspects of medicine, such as diagnosis, therapy, special pathology, and practical surgery. In the late 12th century, the Kitab al-Mansouri was translated into Latin by Gherardo da Cremona, then active as a translator of Arabic scientific works in Toledo, Spain. The title under which this work circulated in the West is Liber medicinalis ad almansorem or simply Liber almansoris. The ninth section of the book, a detailed discussion of medical pathologies of the body from head to toe, became particularly famous and circulated in autonomous Latin translations as the Liber Nonus. This section of Al-Razi's work was extensively copied and commented upon until the 17th century. The manuscript presented here is embellished by rubricated headings and shows various marginal notes, including a very interesting extensive note in Amharic letters preserved early in the work.