The Book of Medicine by al-Rāzī (d. 925/313 H), known to Europeans as Rhazes or Rasis, is one of the works fundamental to the organization of medieval medicine. It comprises nine chapters. Translated into Latin by Gerard of Cremona (d. 1187 AD), it was known as Liber ad Almansorem. The ninth chapter, on therapeutics, frequently circulated by itself under the title Liber nonus ad Almansorem. In the Renaissance many editions of it were printed with commentaries by prominent physicians (as for instance the incunabulum Liber nonus ad Almansorem, cum expositione Silani de Negris. Padua: Bartholomaeus de Valdezoccho, 1476). Although the ninth book of the Liber ad Almansorem had already appeared in numerous editions with commentaries, the one presented here would appear to be intended for the use of students. It is not improbable that it was this very edition which was used by the renowned anatomist Andreas Vesalius while a student at Paris, as his inaugural dissertation, printed in 1537, was a paraphrase of the ninth book of Rhazes. Vesalius praised Rhazes’ skill as a physician and compared his writings favourably with those of the Greeks.