The science of medicine was developed and practiced by eminent doctors in the major cities of the empire; both in Late Antiquity and in Middle and Late Byzantium, many studies were written on pharmacology and the means suitable for treating patients.

The works of the great Greek physicians Hippocrates and Galen formed the foundation of Byzantine medicine, which was further developed and enriched.
 
The practice of Medicine
Byzantium made a significant contribution not only to the theory of medicine, but also to the fields of botany, pharmacology and surgery. Indicative of this is the recording of around 700 animal, vegetal and mineral substances suitable for the preparation of medicines, as well as over 200 kinds of surgical instruments. Indeed, the advanced level of surgery can be surmised from news of an operation to separate conjoined twins from Armenia, though neither of them survived.

Written references inform us that hospitals were charitable institutions operating under the supervision of the Church. In the early centuries they were called inns or hostels, and seem to have functioned as hotels where sick travellers could receive rudimentary treatment. From the 6th century onwards they were used exclusively for hospitalization. The major hospitals in 10^th century Constantinople were St. Sampson’s and the Euvoulos Hospital, which had doctors, nurses and ancillary staff. However, the most important hospital in the capital was that founded by Emperor John II Comnenus at the Monastery of Christ Pantocrator in 1136 - an institution containing a nursing home, a leper hospital and a hostel (hospital) with outpatient clinics and fifty beds, divided into five wards specializing in surgery, ophthalmology, gastroenterology, gynaecology and pathology. The personnel consisted of doctors, trainees and helpers, a female doctor for women, midwives and nurses; there were also apothecaries, cooks, bakers, washerwomen and cleaners, servants and doormen. Facilities included toilets, a bath house, a pharmacy, doctors’ areas, laboratories and auxiliary spaces for the staff. Of the aforementioned institutions, perhaps the only one to survive to the end of the 13th century, if not later, was St. Sampson’s Hospital.

The high level attained by Byzantine medicine is evidenced by the complex techniques involved in the preparation of drugs, the surgical instruments and the specialties which evolved (ophthalmology, obstetrics and gynaecology, dermatology, dentistry, cardiology, orthopaedics), as well as by laboratory testing. Recent research points out that it was mainly the rich who went to hospitals or private doctors, while the poorer generally resorted to the churches of saints famed for their healing powers, where they would stay in the hope of a miracle. Magic amulets were commonly worn to ward off diseases or treat them, and astrology and horoscopes were employed to diagnose illness or make health-related predictions.
 
Medical writings
In Late Antiquity, important names in medicine were: (a) Oreibasius, commissioned by Justinian to write the Medical Collections, a summary of the works of Galen, as well as Euporista, giving a list of drugs easy to prepare; (b) Aetius of Amida, who lived in the reign of Justinian, studying in Alexandria and Constantinople. He wrote sixteen medical science studies later organized into four books (Tetrabibli), of which that dealing with the anatomy and physiology of the eye is considered the most important of its kind before the Renaissance; in the other books he refers to drugs and the effective use of herbs, gives a detailed description of intestinal tapeworms and shows interest in urological problems and arthritis. He is, however, given to departing from scientific knowledge and in some cases recommends the use of amulets to ward off the evil eye; (c) Alexander of Tralles (brother of Anthemios, architect of Agia Sophia) who specialized in the properties of herbs, extending the work of Dioscorides (a major 1^st century physician, pharmacologist and botanist); (​​d) Paul of Aegina, who recorded his knowledge of gynaecology, toxicology and therapeutics in his Medical Compendium in Seven Books, which became also known to the Arabs; (e) Theophilus, a 7^th century doctor who wrote On Urine, where he describes ways of diagnosing diseases based on a detailed analysis of the characteristics of urine.

Writing in the field of medicine was similarly productive in Middle and Late Byzantium, including works such as: (a) The Anatomy of Gender by Meletius the Monk, referring to human anatomy and physiology; (b) Leo the Doctor’s Medical Compendium, on issues relating to the theory of medicine, remedies and surgery; (c) The Compendium of Disease Treatment by Theophanes Chrysobalantes; (d) the Medical Compendium by Simeon Seth; (e) Dynameron by Nikolaos Myrepsos, who gathered 2,656 prescriptions for eye drops, enemas, ointments, pain relieving medications, powders, etc., in what remained the official pharmaceutical code in the West until the 15th century; (f) the Medical Method by Joannes Actuarius, etc.

We also learn about diseases from references in the writings of non-specialists, such as secular and church writers. As was only natural, Byzantine medical knowledge was transmitted to other peoples, as in the instance of the Arabs, with whom contact was established in the 7th century, and the Armenians from the 10th century on.