A bimaristan (Persian: بيمارستان, romanized: bīmārestān; Arabic: بِيْمَارِسْتَان, romanized: bīmāristān), or simply maristan,^{[clarification needed]} known in Arabic also as dar al-shifa ("house of healing"; darüşşifa in Turkish), is a hospital in the historic Islamic world. Its origins can be traced back to Sasanian Empire prior to the Muslim conquest of Persia.^{[page needed][full citation needed]}

Bimarestān is a New Persian word inherited from the Middle Persian wēmārestān (𐭥𐭩𐭬𐭠𐭫𐭮𐭲𐭠𐭭), from wēmār "sick, ill person" plus the suffix -stan "place, location."^{[page needed]}

In English literature, the term designates institutions of medicine in the medieval Islamic world. It is still used sometimes in languages of Persianate societies to refer to modern hospitals or specific types of medical institutions.

Many centers of health in antiquity helped shape the ways Muslim scholars would pursue the study and advancement of medical science.

Mobile hospitals were the first version of the bimaristans. These mobile versions carried medications, food, and water, and traveled with physicians and pharmacists to aid those in need. According to tradition, the first mobile bimaristan was set up in a tent by Rufaidah al-Asalmia in 627 CE during the Battle of Khandaq. Later on, these mobile care centers would evolve from one or two tents to enormous units of medical care equipped with medicinal herbs, food, physicians, and pharmacists. Under the Seljuq Sultanate reign of Muhammad Saljuqi, a single mobile care center required 40 camels for transportation. The idea was to be able to better extend medical care to rural communities that lived on the outskirts of major cities. The services provided from the mobile hospitals transitioned into the other Islamic hospitals as time went on.

The Umayyad caliph al-Walid I is sometimes credited with establishing the first permanent bimaristan in the Islamic world in Damascus in 707, but this has been disputed by historians. The claim is largely based on the writings of later medieval historians such as al-Tabari (d. 923) and al-Maqrizi (d. 1442). Modern historians Michael W. Dols and Douglas Morton Dunlop concluded that some of the early historical sources suggest that al-Walid I created something like a leprosarium (a segregated hospice for lepers) rather than a hospital, consistent with contemporary Byzantine practices. Historian Lawrence Conrad concluded that al-Walid did not establish a hospital, and this view was accepted by multiple other historians, including Peregine Horden and Peter E. Pormann. More recently, Ahmad Ragab argued that there is no evidence that al-Walid's foundation resembled the later bimaristans of the Islamic world, which were more sophisticated medical institutions, but that there is evidence he would have established charitable institutions offering shelter for lepers, the blind, and the handicapped. These likely continued or competed with existing Byzantine charitable institutions of the era and may have formed a precedent that was continued by later Muslim institutions.

The first bimaristan proper was more likely the one founded by the Abbasid caliph Harun al-Rashid (r. 786–809) in Baghdad. This foundation was inspired by the hospital and medical school of Gundeshapur in Khuzistan (present-day Iran), which had been established since the Sasanian period and had brought together the medical traditions of ancient Greece, Iran, and India. According to the traditional narrative, Harun al-Rashid summoned from Geundeshapur a Christian doctor named Jibril ibn Bakhtishu, whom he charged with establishing a state hospital in 787. The details of this story have been questioned by Dols, who argues the hospital may have actually been founded by the Barmakid vizier Yahya ibn Khalid under al-Rashid. Nonetheless, he notes that historical records demonstrate that state hospitals were already a well-known feature of the Abbasid realm by the first decades of the 9th century. Ragab also questions the accuracy of the traditional account but notes that the bimaristan was evidently a well-known insittution in Baghdad in the 9th and 10th centuries.

Though the Islamic realm was very large, Baghdad, Damascus, and Cairo housed the most well-known bimaristans for much of their history.^{[page needed]}