During the Middle Ages (500–1350) medicine became institutionalized; the first public hospitals were opened and the first formal medical schools were established, making health care (formerly administered only in the home) more widely available and improving the training of doctors. These developments had been brought on by necessity: Europe saw successive waves of epidemics during the Middle Ages. Outbreaks of leprosy began in the 500s and peaked in the 1200s; the Black Death (the bubonic plague) killed about a quarter of the European population; and smallpox and other diseases afflicted hundreds of thousands of people. Consequently, many hospitals—meant to serve the poor—were established, as were the first medical schools, some of them associated with universities that were then forming, such as the University of Bologna (Italy) and the University of Paris (France). In 900 the first medical school was started in Salerno, Italy.

European physicians during the period were greatly influenced by the works of Persian physician and philosopher Rhazes (or Razi; c. 865–c. 930). Considered the greatest doctor of the Islamic world, Rhazes’s works accurately describing measles and smallpox were translated into Latin and became seminal references in the Christian world as well. Another prominent Islamic, the scientist Avicenna (or Ibn Sina; 980–1037), produced a philosophical-scientific encyclopedia, which included the medical knowledge of the time. In the West, the work became known as Canon of Medicine and with its descriptions of many diseases, including tetanus and meningitis, it remained influential in European medical education for the next 600 years.