Technology & Medicine › Medieval › Islamic Golden Age science and medicine
Al-Razi (Rhazes)
c. 865–925· Person· Medicine & surgery
Well documentedSolid records, physical evidence or scientific consensus.
Persian physician, chemist and philosopher who ran hospitals in Rayy and Baghdad and first clearly told smallpox from measles.
See it on the Technology & Medicine map →How it works
Born in Rayy, near modern Tehran, al-Razi directed hospitals there and in Baghdad. His treatise on smallpox and measles explained how to tell the two diseases apart. He kept careful case notes, described comparing treated and untreated patients, and wrote Doubts about Galen, questioning the master where observation disagreed. Students compiled his notebooks into al-Hawi (The Comprehensive Book), a vast medical encyclopedia. In chemistry he classified substances and described distillation equipment.
Why it mattered
He modelled medicine based on bedside observation and records rather than authority alone; his books were Latin textbooks in Europe for centuries.
Legacy and how we know
Surviving Arabic manuscripts and Latin translations (al-Hawi as Continens, 1279; the smallpox treatise, reprinted many times), plus biographies by Ibn al-Nadim and others.
Still unknown or debated
The story that he chose the Baghdad hospital site by hanging meat to see where it rotted slowest is probably legend.
Connections (3)
▸Al-Razi (Rhazes) ran early Hospitals (bimaristans)Well documented
The connection
Al-Razi directed the hospital in his home city of Rayy and later one in Baghdad. He used the wards as school and laboratory: patients saw junior students first, then seniors, then him, and he recorded cases, treatments and outcomes. His practice helped make the bimaristan a place of teaching and clinical observation, not just shelter.
When and how
Rayy (near Tehran) and Baghdad, around 900, under the Abbasid caliphate.
How we know
Biographers such as Ibn al-Nadim and Ibn Abi Usaybi'a record his posts and teaching; case notes in al-Hawi describe hospital patients.
Debates and open questions
Which Baghdad hospital he led, and when, is unclear; a later tale links him to the Adudi hospital, founded in 982, decades after his death.
▸Al-Razi (Rhazes) first distinguished the smallpox later prevented by Vaccination (Jenner's smallpox vaccine)Mostly agreed
The connection
Around 910, the Persian physician al-Razi wrote the first known clear account telling smallpox apart from measles, describing its signs and course. Clear diagnosis came before prevention: Jenner's vaccine, nine centuries later, targeted the same disease al-Razi had defined. The link runs through medical knowledge, not a direct step.
When and how
Baghdad and Rayy, near modern Tehran, around AD 900–925; his treatise was later translated into Latin and printed in Europe.
How sure are we?
His treatise On Smallpox and Measles survives and was widely translated and printed; there is no evidence Jenner relied on it directly.
Debates and open questions
Earlier texts from China (Ge Hong, 300s) and India may describe smallpox; who wrote the first account depends on how strictly they are read.
▸Al-Razi (Rhazes) was a key source for Ibn Sina's Canon of MedicineMostly agreed
The connection
Al-Razi's al-Hawi was a huge, loosely organized notebook of cases and quotations from Greek, Indian and Arabic authors. A century later Ibn Sina drew on material like it, including al-Razi's clinical descriptions, but arranged everything into the tight, systematic Canon. Later doctors often contrasted them: al-Razi the bedside clinician, Ibn Sina the systematizer.
When and how
Rayy and Baghdad, about 900–925; the Canon was completed in Hamadan, Persia, around 1025.
How sure are we?
The Canon's content overlaps al-Razi's works on many diseases, including smallpox, but Ibn Sina rarely names his sources, so the debt is inferred.
Debates and open questions
Ibn Sina scorned al-Razi's philosophy; how directly he used al-Hawi, versus al-Majusi's Royal Book, is debated.