The article makes an attempt at the presentation of medical works written by Oribasius (ca. 325 – ca. 400 A.D.), well educated physician from Pergamon, and a close friend of Julian the Apostate. It discusses the content of the treatises, reasons for their compiling and circumstances accompanying the creation of three of his extant writings, notably Collectiones medicae, Synopsis ad Eustathium filium, and Libri ad Eunapium. Moreover, the study presents available information about his lost medical work, whose title is now unknown. The authors focused on these parts of Oribasius’ works, which concern food and dietetic, i.e. five books of Collectiones medicae (from I to V), book IV of Synopsis ad Eustathium filium and a part of book I of Libri ad Eunapium. The above-mentioned books enlist the most important foods like cereals, cereal products (breads, cakes, groats, pancakes), vegetables, fruits, meats, fishes, and seafood, dairy products, soft and alcoholic drinks as well as enumerating some specific diets and groups of food divided according to their properties or influence on human body. An important part of the article is a succinct presentation of sources of Oribasius’ dietetic expertise, and moreover a brief discussion of the medic’s impact on medical systems in three different cultural circles, namely the Byzantine, Arab, and Latin. The authors’ research corroborates the already existing view that major dietetic parts of Collectiones medicae, Synopsis ad Eustathium filium and Libri ad Eunapium are based on writings of Galen (which he, however, reworked with a view of their simplification), but there are many fragments taken from other authorities, for instance Pedanius Dioscurides, Athenaeus from Attalia, Diocles of Carystus, Rufus of Ephesus to mention but a few. As for medical authors, who excerpted or translated Oribasius’ works, the most renowned are Aetius of Amida, Paul of Aegina, Alexander of Tralles, Hunayn ibn Ishāq, and the representatives of the medical school of Salerno. Finally, the authors claim, that Oribasius’ heritage is important especially for two reasons. First of all, it helped preserve a large amount of citations from ancient works, which today are lost, and known only thanks to the physician’s painstaking work. Secondly, it contains a cornucopia of information about food, which reflect culinary habits of Late Roman society, and specifically of the Late Roman food market.
