The **history of medicine** is the study of the evolution of medical treatments, practices, and knowledge over time.

Not much is known about medicine in prehistoric times when there were no written records, but it is clear that it was very different in different places. Archaeology has shown that some Neanderthals had healing practices with plants. There is also some evidence of dentistry. 

Under the Babylonians there is written evidence of diagnosis, prognosis, physical examination, and remedies in the 11th century BCE. There are many medical clay tablets from Mesopotamia. They show measures to prevent the spread of disease, accounts of stroke, and an awareness of mental illnesses. We have many medical documents from Ancient Egypt. Some are in magical terms but some show understanding of anatomy. According to Herodotus, "the practice of medicine is so specialized among them that each physician is a healer of one disease and no more."

There is evidence of traditional Chinese medicine from the Zhou Dynasty, and of Ayurveda in India from the same time. Ancient Greek medicine seems to have developed slightly later. Hippocrates and his followers were first to describe many diseases and medical conditions. Galen's theory of humors came from ancient medical works and it was a powerful influence on Western medicine until the 19th century. There were thought to be four humors, or bodily fluids that are linked to illness: blood, phlegm, yellow bile, and black bile.  Herophilos at the medical school of Alexandria developed the study of human anatomy by dissection. With Erasistratus he mapped out the course of the veins and nerves across the human body and studied the brain. Ancient Romans invented many surgical instruments, such as forceps, scalpels, cautery, cross-bladed scissors, the surgical needle, the sond, and speculas.

Constantinople stood out as a center of medicine during the Middle Ages. Islamic medicine grew at the same time, as Greek medical works were translated into Arabic. The Persian polymath Avicenna has been called the "father of medicine".  The first Islamic Hospital opened in 805 CE by the Abbasid caliph Harun al-Rashid in Baghdad. Muslim hospitals developed into centres of teaching and research from the 16th century. They had separate wards for male and female patients, pharmacies, medical record-keeping, sanitation and hygiene. Their ideas spread into Europe.  After 400 CE, the study and practice of medicine in the Western Roman Empire had gone into deep decline. There were thousands of monastic hospitals in Europe, but the care was poor and mainly palliative.

In the 12th century, universities were founded in Italy, France, and England, which soon developed schools of medicine. Training of physicians began at the University of Bologna in 1219. It was largely lectures and readings of Hippocrates, Galen, Avicenna, and Aristotle. Such care as most people got in Europe was delivered by people who had no training. 

The Renaissance saw an increase in experimental investigation, particularly in the field of dissection and body examination. In 1628 the English physician William Harvey made a ground-breaking discovery when he correctly described the circulation of the blood. Bacteria and protists were first observed with a microscope by Antonie van Leeuwenhoek in 1676.

There was little advance in controlling infections. Most people believed that infections were caused by foul odors called miasmas. Many women died of postpartum infections in hospitals because doctors did not wash their hands. In 1847 in Vienna, Ignaz Semmelweis dramatically reduced the death rate of new mothers by making doctors clean their hands, but his work was rejected for many years.  Louis Pasteur and Robert Koch developed germ theory in the 1860s and applied it to the epidemics of cholera. Pasteur went on to develop vaccinations.